A term grown out of the alien abduction mythos of the late 20th century. It's when you give a person an "Anal Probe" while they are passed out.
Girl: Did you cornhole me while I was out? Boy: No, it must have been an alien abduction.
By bubba
The night after a lot of drinking when you wake up and can't rememeber the events of the previous night. And, your butt kind of hurts or you have a mysterious bruise that you don't know how you got.
Guy 1: Dude, how did you get that bruise? Guy 2: I don't know, I guess I had an Alien Abduction last night.
By Tempted
The act of waking up naked on your bathroom floor in a puddle of your own stool and vomit after a night of heavy drinking.
His mother found him following an alien abduction, so she washed him off in the shower and put him to bed.
By sixtoe
A group of people who may or may not be from outer space. But who take great interest in you're butthole.
Alien abduction societies are normal. After the victim has been violated. Government types show up, and declare that there's nothing to see. While others are eager to cover it up.
By Iam not Elmer Fudd