Pulled out of your ass. Something that is either completely made-up, or if true, a lucky guess.
Dude 1: How did you get a B+ on this test? You didn't even study!
Dude 2: Rectal extractions.
Dude 1: ???
Dude 2: I was just pullin' answers out of my ass and got lucky.
The fine art of getting someone to lighten up a bit. To help change their point of view.
Mr. Smith is so adamant about not letting his daughter Mary date until she is 27 years old, that he needs to have a rectal broomstick extraction procedure performed.