Two things people don't like: stand-up comedy that is genuinely angry, and public displays of affection.
Plenty of comedians play angry. They throw on the angry comedian costume - leather jacket, Marlboro, imitation snarl - so the crowd knows they mean business! They really are mad about the twist-off caps on cough syrup bottles!
But it is all just a game, and the crowd knows it. That comic in the angry comic costume isn't truly angry any more than an impersonator in an Elvis costume is really Elvis. That is why they laugh; because they know the anger is all make-believe.
Comedy crowds can't handle real anger, so a comedian who shows too many flashes of the real thing usually bombs. Famously "angry" comics like Kinison found ways to codify their anger into signature moves that could signal "anger" without showcasing the authentic anger that kills the mood. Lesson from Comedy 101: Don't Callback in Anger.
People also can't stand public displays of affection. "Get a room!" is a typical taunt to couples who make their feelings too obvious. Yet those righteous "Get a room!" hecklers will pay to tearfully watch a syrupy romantic comedy about a Bedouin who falls in a sand dune and finds his true love hidden under the scorpions. But real affection offends them. They can't stand an unscripted romantic comedy happening before their eyes.
They often say love and hate are two sides of the same coin, and I say these two phenomena demonstrate that. What people find funny is an extremely intimate part of them, so maybe it makes sense they need play-acted comedy emotion the same way they need play-acted romantic emotion? At least the people on the subway who scoff at the smooching couple can say they didn't request a romantic show. What is the major malfunction of the paying comedy crowds who shrink when they catch a true glimpse of the hate side of the coin?