Ur mom is a basic comeback to an insult, or practically anything that someone says.
PRACTICALLY ANYTHING SOMEONE SAYS
Jonathan: Yo, Lexi. What’d you have for dinner last night
Lexi:I had ur mom last night.
INSULT COMEBACK.
Tyler: You’re fat
Derek: Ur mom fat
A famous phrase that young pupils use, normally to offend the kid they said it to.
Joe Bookster: "Whats answer 19?"
Kevin Hamsterson: "Ur Mom!"
A comeback for pretty much anything tbh
Examples:
Person 1: Hey smell this, it smells like blueberry
Person 2: -sniff sniff- EWW WHAT IS IN THAT THING?!
Person 1: Ur mom
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Another Example:
Carter: Omg, are you dumb?! Humans BREATHE air, not memes!
Julie: Oh, well your mom does. And so do I.
Carter: ...Well...ummm...I-...
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AND ANOTHER EXAMPLE
James: Oh come on, can't you play football with me today?
Liam: Well, the thing is I have a to-do list every day now.
James: Oh...well what's one thing on it?
Liam: Ur mom
James: ...
James: Uhm...oh look, my football is running-errr rolling away! I'll see you tommorow!
Liam:
a funnily rude way of saying something so called funny or responding to someone talking and you're annoyed.
"so then we kissed!!!"Sookie said happily. "Ur mom" Lorelai announced.
An annoying, yet addictive slang for when someone has nothing else to say.
Whoever: "What's your favorite color?"
You: "Ur mom."