What is Idym?
Just because idym doesn't mean you have to get mad.
An acronym for I Did Your Mom.
Bob: Hey man, IDYM.
Joe: What does that mean?
Bob: I Did Your Mom!
Joe: Hahaha, you owned me :(
Bob: Yes, yes I did.
An acronym for "I Drink Your Milkshake." Normally used to denote that someone has been "owned" or has had their thunder stolen.
Dale the Dinglish Speaking Derelict: Look at how long my Dinglish drawl is.
Long Dong Assler: Dale, IDYM. I would have to fold mine in half to be the same length as yours, you crotch goblin.