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4.
Slang for "your mom" which is the ultimate come back in any situation, but it is said so quickly that it sounds like one word.
-Damn, where'd you get such an ugly shirt?
-yermom!
by Chelsea March 07, 2004
 
1.
A great insult to fling at people. Or just something to say when there is nothing else to fill the void. Also, the source of many dirty jokes.
A) "Yer mom is so -insert insult here-

B) Person 1: "Hi, how are you?"
Person 2: "Yer mom!"

C) Person 1: "Hey, you poked a hole in my balloon! I hate you!"
Person 2: "I poked a hole in your mom last night."
by soniahazard April 28, 2004
 
2.
the best insult in my mind. it also works if you get asked a question and dont want to answer it or just feel like wierding someone out. it also works if you get insulted. also one of the best starts to jokes. (a.k.a. yer mom jokes)
Jorgé the muffin: you suck
Bob: yer mom sucks

Jorgé the muffin: whats up?
Bob: yer mom. what else.

Jorgé the muffin: hey you wanna go out?
Bob: yer mom wants to go out.

Bob: Yer mom's so stupid that she got run over by a parked car.
Bob: Yer mom's so fat, she needs a watch on both arms because she covers two time zones.
Bob: Yer mom's so slow it takes her two hours to watch the tv show 60 Minutes.
 
3.
Widespread use of this phrase was brought back to life after the movie Napolean Dynamite hit theatres. This is generally used as an insult, though it can be thrown into a conversation at any point in time.
Andrews - "Yer mom's so fat... that when we tried to graph her on our calculator... there was a stack overflow error."
by sdb2404 March 01, 2005
 
5.
A popular and fun way to insult someone.
You suck man, but not as good as yermom.
by d'z Nutz on Yo chin. March 11, 2003
 
6.
as in who was done last night
dude 1: what did you do last night?
dude 2: yermom.
by pete March 02, 2003
 
7.
Good way to annoy people that ask too many questions.
<bob> Huh?
<bob> I don't get it
<bob> wait, why?
<bob> WHO WAS IT DUDE
<Jag> yermom
by Jagfire March 10, 2003