Missed the edit widow.
So does Bill Paxton.
They also made Donkey Punch into a film:
A bunch of Eurotrash douchebags invite some Euro-hos onto a yacht. After a during a night of drinking, drugs and sex, one of the dudes tries to experiment with this “Donkey Punch” thing they’ve been talking about all day. He accidently kills one of the girls and hilarity ensues.
But the fact that you assume they are dirty is exactly what the OP is getting at. They don’t mean anything–yet. Give me a little time on Urban Dictionary and…
I have a friend who tells a hilarious story about taking some obnoxious Canadians round China. The story culminates in him saying “so I didn’t bother telling them that they were eating donkey dick!” If it was any other animal, no way near as amusing.
Here’s a handy button you can press to generate a random noun.
It took twenty-nine presses before I got a word that sounded dirtier with “donkey” in front of it. (“Donkey fluid.”) Another one came along only seven words later, though. (“Donkey grunt.”)
My conclusion is that “Donkey” is a serviceable intensifier for words which already have some dirty connotation or association, but doesn’t really dirty up neutral words, although it frequently makes them funnier. “Donkey Sonata” is funnier than “Sonata,” but it doesn’t sound particularly dirty to me.