Last week in Stephen Pastis's Pearls Before Swine, a comic strip appreciated by no one so much as it is by Stephen Pastis himself, Rat proudly announces his new comic strip. He declares he's done his research and noted comic strips can't mock race, religion, ethnicity, sexual orientation, or mental or physical illness; and therefore he based his strip on mocking fat, dumb, bald guys who bought those singing mounted fish.
I put aside my observation people who complain political correctness strangles humor are typically unfunny people sulking that their lame material doesn't get laughs. The question is why is it necessary to mock any ``types'' in being funny. But that's easy to answer: because it is funny. Specifically, it's funny when a person is put in an ironic situation, or forced to do something they're unable to, or stumbles into something embarrassing, or puts a great effort into a trivial reward, or so on. That's by far not all kinds of comedy, but it is a steady base.
To know what is an ironic situation for that character, or one that's beyond their abilities, or such requires knowing the character. There's a funny story in Felix Unger searching through a garbage dumpster, as example, that wouldn't be as funny for Oscar Madison, and wouldn't even be a joke for Oscar the Grouch. That's where the need for stereotypes comes in: there's not always time to establish or create characters.
A stereotype can get quickly to the situation and, hopefully, punch line; presumably any obsessively clean person would be funny in a dumpster. We need to recognize enough of the person to get the joke, but everything past that is gravy. Still, being able to tell a joke with good characters makes a better laugh; it's funnier when Groucho Marx is trying to get out of the opera than when it's just The Guy In Our Story.
Sometimes there's no space for setting character, as in my joke the other day about Mad Max live-action roleplayers and Star Trek/Civil War reenactors. I could write a comic dialogue with characters representing both types, but that'd take more space than I wanted to give the topic, and I doubt it'd make a funnier joke.
I should note that good writers, when they have room for a character -- such as, well, a comic strip where a character may be expected to appear several panels a day for several days, maybe a week, even if the character doesn't become a regular -- will typically use only as much of the stereotype as absolutely needed and then fill out the rest with original characterization. But sometimes the role calls for (say) a store clerk whose only trait is he can't (or won't) get the order right, and nothing more, and there's no unique personality which can be fit into that.
So why does Rat's whining bug me, when I do, and expect to continue, making fun of what are really stereotypes? He's upfront about mocking the fat-dumb-and-bald, and only wishes he could make fun of mental illness; it seems like attitude must be part of it. Rat's an arrogant character and his jokes are more often cruel, which annoys me to no end. It seems there's something more, though I don't know just where.
Trivia: The first four stations of the Mutual Broadcasting System were WGH, Chicago; WLW, Cincinnati; WXYZ, Detroit; and WOR, New York. Source: A Pictorial History of Radio, Irving Settel.
Currently Reading: The Kaiser's Merchant Ships in World War I, William Lowell Putnam.