A small goblin-like animal with a Hitler mustache that resides inside a person's ass. At night, ass nazis leave their dwellings and venture outside to steal your underpants. See also: "Underpants Gnomes".
Sexual Shenanigans whereby a male intends to perform anal sex on his unexpecting partner and does so my Tom Foolery and leads his partner to beleive that the occurance of the unexpected anal sex penetration was merely the direct result of a result of cockslippage.
Howard couldn't wait to have a little bit of his girlfriend's Brown Eye so he pulled of a little Assnanigans and slipped out mid-stroke making Sonja squeal with delight.
Roger: Hey Carl. How was your date with Rhonda last night?
Carl: Oh it was good Brahhhh! I pulled some Assnanigans!
Roger: Sweet!
The Art of Being an Ass Nazi is when someone is so up oneself's own ass, there is no fun to be had and Extermination of small races can be found. One that has been called ass nazi should be attacked in their sleep and a fake moustache be drawn on their face and when the person speaks, everone else must reply 'Heil Hitler'