Idioms or phrases to answer to obvious (yes) questions?

In some contexts, "obviously".

A computer salesman to an elderly gentleman who was asking a lot of "dumb" questions.

Salesman: Are you new to computers? Gentleman: Obviously.

I found a few websites that list out some examples and a suggested term to search for on Google.

Witty Ways to Say “Yes”

• What’s the opposite of no?
• If I was a regular jerk, I’d say no to this one.
• Is the mitochondria the powerhouse of the cell?
• My two thumbs are standing in salute.
• Is the sun hot?
• My guts tell me that you are worth all the trouble.
• Do fishes swim?
• Something tells me I should trust you. But, I think it's just your words.
• Is one plus one equal to two?
• It appears that you have read my mind.
• Are boogers salty?
• Come on, humor me.
• Do pigeons fly?
• Tell me more.
• Is the pope catholic?
• Do vacuum cleaners suck?
• Is water wet?
• Is the hypotenuse the longest side of a triangle?
• Does a bear live in the woods?
• I’ll answer you with my favorite ‘Y’ word—Yes!
• Is the sky blue?
• I totally ‘scored’ getting asked by you. Yes!
• How do you spell yes?
• Would you take ‘yes’ for an answer?
• I haven’t said no yet, right?
• Would I be too tall for you if I were standing on cloud 9?
• Am I not holding my two thumbs up?
• There’s a 100% chance that I’m going say yes to that one.
• Like a dog wagging its tail in excitement!

Green’s Dictionary of Slang

• does a bear shit in the woods?
• Is the pope (a) Catholic? phr.
• do beavers piss on flat rocks?
• does a bird have wings?
• do sheep wear sweaters?

A Google search of "sarcastic interrogative affirmatives and negatives" produces more...

A lecture on the use - Archer Taylor Memorial Lecture 2006: Is the Pope Still Catholic?: Historical Observations on Sarcastic Interrogatives

Sarcastic Interrogative

sarcastic interrogative. noun. Defined by folklorist Charles Clay Doyle as “stock questions with glaringly obvious yes or no answers. The function of each such question is to respond derisively to a prior query, itself calling for a yes or no answer so as to suggest that the answer to the original query is too obvious to be worth proffering seriously.” Perhaps the most famous example: “Is the Pope Catholic?” And perhaps the most canonical: “Can a duck swim?”

Some colorful examples:

• Is a frog’s arse watertight?
• Does Barbie have a plastic fanny?
• Is a pig’s butt pork?
• Does a snake have knees?