If you think about it, a good laugh is physiologically a full body spasm, a shaking off of tension the way a wet dog shakes off water.
If I mock, for example, someone’s accent, then yes, it is an aggression of sorts, but one which takes energy from a deeper aggression, which actually facilitates peace and connection if the person laughs with me. In effect, I am saying you, Italian/Chinaman/Arab/etc., make me uncomfortable, but if you laugh with me, I will begin to process you unconsciously as safe.
Ethnic or other something-centric “humor” can certainly be a means of channeling hate. But used with some skill humor is a social necessity. Without it, anger has no outlet BUT violence of some sort, which begins in emotional violence or perhaps, pace Orwell, linguistic violence.
Political Correctness, in other words, as most of us sense intuitively, is an angry, stubborn, inflexible mindset which relies on emotional and social violence and which includes no social mechanism for incorporating spontaneous change, socially deep interconnection, or anything approaching an emotionally intelligent way of dealing with life and people in general.
It consists, I will add, primarily in the demand that we suppress utterly all honest, authentic, spontaneous impulses—impulses which come from our deep, true self—in favor of emotional constipation which cannot but make people angry and dissatisfied.