Are there any "fake" French words used in English?

Of course.

For instance, the word partez is sometimes used (jocosely and otherwise) to mean party (the noun or verb).

Count de Monet is how a stingy person is sometimes referred to (to their face).

I recently made an attempt on ELU to introduce payage (for tollage). A long and intriguing discussion ensued.

Toot sweet is more or less ubiquitous.

There is plenty of French-like nonsense, mostly parodied, in the English and American literature. One example that springs to mind is Charlotte's "departez!" (she means to say "depart!") in Nabokov's Lolita. The same novel mentions our especial fondness of Ball Zack.

(Needless to say we're also fond of Bow Mar Shay, Flaw Bear, Due Mar, and constantly Parley Voo about various stuff going on in the province of Sham Pain).

Generally, it is the belief of all people worth speaking of that every educated person must speak English no matter where he was born; but every educated person who also thinks of himself/herself as intelligent must also speak French. It is, after all, the language of the cultured class. I'm almost not joking.

There's a cafe just north of the Plus Maw Bare in Paris where my painting of the Shut Lay hangs. In case you're wondering what this Plus Maw Bare is, here's my painting of it:

P.S. On @SevenSidedDie's request: t To those who don't get it (for whatever reason):

1. Partez (pronounced par-TAY) is what some people think, or pretend to think, is the French word for "party". As in "Let's party!"

2. Count de Monet: Comte is the French word for "Count," but this is ignored by the joker. "Count the money" is the implication here.

3. Payage means "toll" in French. "Tollage" means "toll" in English. "Fundage" means money secured for a project (the project can be anything, including, but hardly limited to, buying food and paying rent).

4. Toot sweet: a phonetic rendering of toute de suite. Means "right away" in French. Toot: to make a short, high sound with a horn or whistle. Sweet: being or inducing one of the basic four (some say six) taste sensations.

5. Departez! - means exactly nothing in French. But it does look a lot like the English verb "depart". Assumptions are sometimes - a bit cavalierly, perhaps, which makes them funny.

6. Ball Zack: phonetic rendering (a little bent to fit American pronunciation) of the name Balzac (as in Honore de Balzac, famous French novelist and coffee lover).

7. Bow Mar Shay: Pierre Beaumarchais, French dramatist and dissident.

8. Flaw Bear: Gustave Flaubert, French novelist.

9. Due Mar: Alexandre Dumas, Pere and Alexandre Dumas, Fils, father and son, French novelists and dramatists.

10. Parley Voo: from "Parlez-vous Français?" ("Do you speak any French, you moron?"); here: just "talk" or "speak". The "vous" part makes it sound sophisticated (in some people's opinion).

11. Sham Pain: Champagne, of course.

12. The Plus Maw Bare: Place Maubert.

13. The Shut Lay: Place de Chatelet.

14. Lolita: here, a novel by Vladimir Nabokov, in which, among other things, a middle-class housewife writes a love letter to a man whom she is trying to impress by using what she thinks is a French word.

I hope this helps.

Parley - To treat, discuss terms; esp. to hold a parley (with an enemy or opponent), to come to parley. (OED)

This is a French word that has a different English meaning.

"Double entendre" is a fake term made of two real French words which is only understood by English speakers and has no real meaning in French:

https://en.wikipedia.org/wiki/Double_entendre#Etymology

Something that crossed my mind is "Omelette du fromage". I don't know if it is used by English speaking people but I do know it is a well known phrase among some people. From Urban Dictionary:

The amazing phrase from Dexter's laboratory in the episode "The Big Cheese", when he listens to a French recording overnight to learn said language. This consequentially gets stuck on repeat, on this phrase. The next day all he can say is "omelette du fromage", actually working to his advantage in everything he does (except at the end, when his lab blows up).

Although meant to depict "cheese omelette", this phrase is grammatically incorrect. You should say "omelette au fromage", which means "an omelette with cheese".

Despite this, people still say the phrase "for the lols."

petite in English is used as an adjective for a woman or girl that is both short and slender.

Kylie Minogue is petite

Kylie Minogue est toute menue or Kelly Minogue est un petit bout de femme.

Whereas petite in French is the feminine of petit, which can be used both as an adjective and a noun for just about anything that is small (in size, scope, etc.), little, short, young (les petits; the little ones), or younger (petite soeur; kid sister); (le petit Dumas; Young Dumas: the Dumas' son.)

E.g.

Marie est plus petite que Jeanne; Marie is shorter than Jeanne.

Jean habite une petite ville du Loir-et-Cher Jean lives in a small town in the Loir-et-Cher.

Saint-Cirq-Lapopie est un joli petit village du Lot; Saint-Cirq-Lapopie is a quaint little village in the Lot area.

Tu vois la petite la-bas? C'est ma soeur; Can you see the short woman/gal (also, young little girl) over there? She's my sister.

Je prendrai la petite; I'll go with the small/short one.

And "cul-de-sac". French call a dead-end street "impasse".

One interesting case is how chaise longue has long since evolved into chaise lounge in some usage in the US.

Coup de grace is sometimes used to mean Mow de lawn. Campers often have En tent Cordial. Fixez les brakes seems to have superseded Reparer les freins

Entrée actually means appetizer in French. the French use "plat principal" ou "plat de resistance" for entrée.

In Eurovision "nul points" or "nil points" are made-up expressions meaning zero points:

When a country finishes with a score of zero, it is often referred to in English-language media as nul points, or sometimes nil points. The correct French for "no points" is pas de points or zéro point, but none of these phrases is used in the contest, as no-point scores are not announced by the presenters.

"Douze points" is also used, meaning the maximum 12 points one country can give another, but that is genuine French.

I think the term you are looking for is false friend, or in French, faux-ami.

False friends are words in two languages (or letters in two alphabets)1 that look or sound similar, but differ significantly in meaning. An example is the English embarrassed and the Spanish embarazada (which means pregnant), or the word sensible, which means reasonable in English, but sensitive in French and Spanish.

Some examples I can think off the top of my head:

Chef - anyone who cooks professionally in English, a boss in French

Ancien(t) - Something that is old in English, but in French, ancien can also mean "the ex-".

Bras - Plural of brassieres in English, the arms in French

Money/monnaie - Any form of negotiable currency in English, loose change in French.

Library/Librarie - A place where you borrow books in English, a place where you buy them in French.

In BrE, as well as in French, "à la mode" means "fashionable". However, in AmE, it means "with a scoop of icecream".

Similarly, interpretations of entrée differ radically, meaning "starter" in BrE, and "main course" in AmE, and "entrance" in French.

A couple words from western USA/Canada, left over from early exploration days:

plew - a beaver skin

Dictionaries claim it to be from the French pelu (hairy), but in mountain man/history buff circles it's often claimed to be from the French plus (more)

parfleche - dry rawhide, or a container made from rawhide. In reality, it's not literally rawhide. It's slightly worked, but not tanned.

from the French parrer flèche i.e. deflect arrows

capote - a coat (historically, a hooded coat made from a wool blanket)

My all time fave is "Voulez vous coucher avec moi ce soir?"

Oh wait. What's that? You say that actually does mean, "Do you want to...?" My bad.

• Patron

First time I traveled to the US, I was quite puzzled by a "Patron Parking Only" sign outside a restaurant.

Patron evolved differently with one of it English meaning being customer while in French patron main acception is colloquial for manager, i.e. translates to boss.

I somewhat hesitated to risk parking my car to a space I thought was reserved for the manager use...

It is quite amusing to see that what used to be the Latin patronus has slightly evolved in English to finally mean client, while the latter precisely comes from the Latin clientes which was the exact antonym of patronus.

• Verge

Another puzzling word I saw in the UK : some road signs show "Soft verge, keep off" or "Soft verge for two miles". That would be "Soft shoulder" in the US and Accotements non stabilisés" in French. "Verge" originally meant rod / wand in both French and English but the meanings highly diverged as nowadays, in French, the word is almost exclusively used as a non slang, medical term for penis / phallus.

• Grapes

As already answered by BlokeDownThePub raisins are French raisins secs but it happens also that Grapes, which comes from the French Grappe ( = cluster/bunch) are French raisins. That means "a cluster of grapes" translates to une grappe de raisin.

• Pet pourri

Once in the New Jersey, I saw a store likely selling pet stuff that was named Pet pourri, obviously a pun with "pet" and "pot pourri". Their authors were obviously unaware the pun was much more funny in French. While Pot-pourri means, I guess like in English, a mixture of dried flowers, Pet pourri means Rotten fart ...

I just found there are several businesses using that name in the US: a similar shop still in NJ, a web site, a grooming place in FL and even a nick name.

• Demand

Not exactly a fake word but there is a serious difference in meaning with the French demande that sometimes lead to issues. A "demand" is an exigeance in French while the French demande is just a (polite) request. I have seen English speaking pissed off by what they thought was an arrogant behavior when unaware Frenchmen were "demanding" something while they really just ask for it.

• Preservatives

English preservatives are French conservateurs while French Preservatifs are English Condoms...

• Reservoir

English reservoirs are French lacs de retenue/lacs artificiels (it used to be réservoir too but that meaning has been lost in current French). French Réservoir is mostly used to express what is in English a Fuel (or any liquid) tank.

• Fabric / Tissue

English fabric is French tissu while French fabrique is English factory. English tissue is mostly used to name what French call mouchoir en papier (Kleenex® too).

• Concierge

English concierges will eventually be named concierges too but currently, most French people are reluctant to call them that way because traditionally French concierges, essentially located in the ground floor of Paris area buildings, are what is called in English janitors/caretakers. Nowadays, these old style concierges have mostly disappeared though.

'Connoisseur' is interesting because it is 'fake' in two ways; the modern French spelling is connaisseur, and the French word refers to knowledge rather than appreciation.

One French word which has (perhaps amusingly) taken on a dramatically new meaning in English (esp. US) is douche:

shower

Of course there exist words as described and they are called loanwords.

From the British Library, we have:

"Loanwords are words brought into one country from another. Words are generally 'loaned' when two different cultures come into contact with each other. This might be because of immigration, trade, fashions or foods, travellers tales, the arts (paintings, books, poetry or film), technologies, wars or colonisation".

Complementing this thought we have in the Oxford Dictionary that loanword is "a word adopted from a foreign language with little or no modification".

HERE is a list of French loanwords used in English, among them, some very well-known: bidet, camouflage, coup d’etat, croissant, cuisine, lingerie, prestige, silhouette, souvenir and voyeur.

In portuguese (my native language), they are known as "estrangeirismo" (foreigness if literally translated). In German and French they are known as "xenisme" with a slight difference in French because of the acute (xénisme).

Would "petty" count? Or has it been part of English so long that it has become an English word?

I would posit that in US English, Fillet qualifies as a Fake French word, merely due to how most people I have known from the US pronounce it (fɪl·eɪ rather than fɪl.ɪt).

In French prune and raisin refer to plums and grapes in their natural state; in English they refer to the dried variety.

I suppose this is because in the old days it was the only way of preserving them for export.

Also there's sacre bleu and zut alors, both expressions of annoyance that nobody actually uses.