Back when Bill Clinton was President of the United States, Al Franken (formerly a Saturday Night Live comedian, now a US Senator) gave him lessons in comedy. He needed these lessons because the press corps expected a certain Borscht-Belt-ish style of self-deprecating humor from a president, but this was not the kind of humor that Clinton, as a Southerner, was familiar with.
This story haunts me, because I’m familiar with Jewish humor, and as a long-time fan of BBC comedy I think I’ve picked up English humo[u]r... but if I have a character who is neither Jewish nor English and I want him or her to say something funny or even slightly witty, how do I come up with wit (sarcasm, irony, hyperbole, etc.) that is appropriate to the character’s background?
(And this is even before worrying about whether or not the joke is funny.)