Ur mom is used when someone asks "what does this look like?" or "who is that?" etc. and you are too lazy to answer
"What is that?" It is ur mom"
“Ur mom” is a roast used by 12 year olds. It is a popular thing for fortnite players will say.
Girl- who is your crush billy ^w^~
Boy- Ur mom
the most legendary group chat ever, no cap on josh
text the ur mom chat about it
ur mom is blowing up omg
i sent a picture of it to ur mom
The worst insult to ever be heard
Person 1: ur mom
Person 2: *dies*