What does ‘shpritz’ mean?

It is Yiddish: shpritz corresponds to the German spritz meaning spray in standard English

It's not actually an English word; it's slang, most likely of German and/or Yiddish origin. These words starting with shm- or schm turn up a bit amongst English speakers with Jewish heritage. That said, the word "schmuck" seems to have entered common usage, at least amongst speakers of American English.

(disclaimer: my knowledge of such things is based purely on watching American TV and movies and hanging out on the internet - I hope my words don't insult anyone.)

From context, I would guess that shpritzing means telling jokes or stories.

spritz or shpritz comes from Yiddish meaning a spray:

spritz 1917, from Yiddish or Ger., lit. "spray." Spritzer "glass of wine mixed with carbonated water" is from 1961.

I don't think it is often used with 'spritzing jokes', but the writer is deliberately using it to draw a connection with Bel Kaufman's Jewish heritage. The use of Yiddish in American writing is common enough in novels and writing. Philip Roth comes to mind when I think of writers of Jewish identity that often use Yiddish words to pepper their writing and draw on their cultural identity.

When used in Jewish jokes, the word has the specific meaning of "in your face," meaning the joke is in your face, like a spray (shpritz) of water. But even more precise is its meaning as soda squirted from a distinctive seltzer bottle as used by vaudeville clown. Thus, the expression attributed to Lenny Bruce that he insults gentiles directly—"spritzing the goyim."

It’s either German or Yiddish. I’m PA dutch, and Schpritz is used to describe a light drizzle or spraying something, like an aerosol can. If your spitting as you talk, you could imagine somebody telling you you’re schpritzing all over me.

Words imported relatively recently in English from another language go through a period during which their status as legitimate English (as opposed to foreign borrowings) may be in doubt. In the case of shpritz, we are dealing with two levels of complication.

First, we have the problem that the spelling shpritz identifies the word as Yiddish, not English. Although use of shpritz is not especially rare in the United States, the word doesn't appear in standard dictionaries such as Merriam-Webster's Eleventh Collegiate Dictionary (2003) or The American Heritage Dictionary of the English Language, fifth edition (2011). On the other hand, it does appear in dictionaries of American English slang—and has for at least 35 years.

From Robert Chapman, New Dictionary of American Slang (1986):

shpritz n A bit or touch; a dose: each a free-associational shpritz of surreal hi-de-ho—Village Voice {fr Yiddish, literally, "a squirt"}

From Barbara Kipfer & Robert Chapman, Dictionary of American Slang, fourth edition (2007):

shpritz n A bit or touch; a dose : each a free-associational shpritz of surreal hi-de-ho—Village Voice {1970s+;fr Yiddish, literally, "a squirt"}

From Tom Dalzell & Terry Victor, The New Partridge Dictionary of Slang and Unconventional English (2006):

shpritz; schpritz verb to squirt or spray US Yiddish [Cited example:] The Irish got schpritzed and schpritzed and schpritzed. —Lenny Bruce, The Essential Lenny Bruce, p. 20, 1967

So it appears that at least since the 1970s shpritz has been a term in active use in U.S. slang or (in what Eric Partridge offers as an alternative language category) unconventional English.

Second, we have the complication that shpritz was preceded into mainstream English by a very similar term from German: spritz. Unlike shpritz, spritz does appear in Merriam-Webster's Eleventh Collegiate:

spritz vb {G spritzen to squirt, spray} vt (1902) : SPRAY ~ vi to disperse or apply a spray — spritz n

But don't let that 1902 origin date in English fool you. The first edition of the Collegiate Dictionary series to include an entry for spritz was the ninth (1983)—before which time people could make the same argument about its legitimacy as a real English word that they are free to make today about shpritz.

But given that Merriam-Webster lists spritz as verb in standard English meaning "spray," and given that Dalzell & Victor defines shpritz (as a verb) as meaning "to squirt or spray" in U.S. slang, how are we to distinguish between spritz and shpritz when someone uses the word in spoken English as a verb? Are they really two different words—one English and one foreign?

In the example that Yoichi Oishi asks about—"At 100 years old, Ms. Kaufman is still shpritzing jokes, Jewish and otherwise, which is in her genes."—the person being described is Jewish and the journalist's use of the spelling shpritzing signals the intention to invoke the Yiddish form of the word, but I can't for the life of me see any difference in meaning between the spraying, spewing, or squirting of jokes implied by shpritzing and the spraying, spewing, or squirting of jokes that would be implied by the spelling spritzing.

I suspect that native English speakers in the United States are not particularly conscious of any distinction between shpritz and spritz, whether used as a verb or used as a noun, and that for all intents and purposes the difference is simply one of pronunciation. Whether you are inclined to view neither as a real English word, both as real English words, or one as real and the other as an interloper, both function in the language as familiar (in the United States) slang terms for "a spray or squirt" (as a noun) or "to spray or squirt" (as a verb).