What people say when the they lack the intelligence to think of any sort of comeback. It's a very redundant phrase. You'll say, "Hey, how's it goin'?" and your mother will be brought into the conversation out of nowhere.

Whomever uses this phrase in an argument, has automatically lost.
Me:Seriously, Napoleon Dynamite sucks.
Them:ur mom
Them:lol
Them:...
Me: Ohhh, original.
Them:STFU ur momz a ho
Me: At least I got one, motherfucka'!
Them has signed off
by Jon March 07, 2005
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a horrible comeback used by total idiots who have nothing better to say. It is often replaced by other nouns in the sentence.
Bob: your an idiot.
Paul Baker: Your Mom's a idiot!

Sally: this homework sucks
Paul Baker: your mom sucks!

Joe: your gay
Paul Baker: Your mom's gay!

by urmomisgay June 20, 2006
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Honestly you can say it for anything. Compliment, insult, describing your great aunt at her funeral! The possibilities are endless!
Ur mom: Hey Jimmy did you get your homework done?
Jimmy: ur mom

Karen: I dEmAnD tO sPeAk To ThE mAnAGeR!!! WhO iS hE!?!
Me: ur mom!
by Tessa2021 February 05, 2020
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joe mama, aka joe mama
you-"hey you know joe"
other person-"no, who is joe"
you-"JOE MAMA"
other person-"what?"
you-" you don't get it? it's ur mom
by ghghhghg October 19, 2019
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Something insulting people say when they don’t know what to say.
Hey Timmy where were you last night?
“Ur mom!”
by Leavemealonebrady May 19, 2019
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