I did say the overdone ethnic "humor" crossed my line. I didn't write a letter of protest, though, because I knew it was my personal line that wasn't shared by everyone else. I just didn't find it funny at all. If you remember a comedian named Andy Kaufman, you might remember that his repertoire included doing standup routines while in the persona of an Indian or Pakistani citizen with a thick accent trying to tell American humor jokes. I found it painful and not at all funny.
Then I got to thinking about what makes people laugh. Now THERE is a thread for the armchair psychologists among us. If you think about it, most punch lines reveal some calamity or some failure on the part of the joke teller or the primary actor in the joke. It might be a tragedy. It might just be the discovery that the person in question was anywhere from a bit slow to stupid to unbelievably dense. But think about the jokes you know, or go look in the Watercooler's "Best Jokes" thread. A large number of them involve someone's misfortune. Puns are not excluded from this because in that case, WE (the listeners) are the ones who were dense in that we didn't see it coming. The late Bennett Cerf was noted for quipping "The pun is the lowest form of humor - if you didn't think of it first."
Basically, we laugh at someone's expense. Let's take an extreme (and I have purpose for that extreme). The Three Stooges were noted for slapstick humor in which Moe and Larry inflicted some humiliation or pain on the third member, whether it was Curly, Shemp, Curly Joe, or someone else. But their form of humor makes some people cringe. But the best man from my wedding was a Three Stooges fan.
Consider comedian Foster Brooks who used to appear on the Dean Martin show. His schtick was that he was a drunkard (when in character). There was the show Laugh-In which was a series of vignettes that included some pie-in-the-face routines as well as some more subtle humor. (Not a LOT of subtle humor.) Or consider Tim Conway from the Carol Burnett Show and one of his most famous routines, the inept dentist. Take a look at the videos on You Tube for the "Blue Collar Tour" comedians.
Please do not think that I have no sense of humor. I can laugh at almost anything - but sometimes in the process, I realize that the humor was at someone's or some group's expense and it gives me pause. It makes me wonder if sometimes, that which makes us laugh does so by incurring in us a sense of "There but for a stroke of luck (or the grace of God, take your pick on this one) go I." Or perhaps "Glad it was him and not me."