What is A Der?
expression showing the idiotic obviousness of a fact
the smurfs are blue
a der is slang for giving head. Used in conversations where the parties describing the act use the word as a substitute for the actual word, usually in mixed company.
Scene: at a crowded party
Candi: Did you see Jonathon over there?
Cyndi: Sure, I just got done giving him a der in the bathroom.