somebody being very obnoxious and replying with two words.
Matthew: Hey what's up!
Francene: Ur Mom
it means your mother, but it is used at the most hilarious times. funny people say ur mom and if you don't think it's funny then you can leave and remove yourself from this page
What did you eat today? ur mom
when somebody wants to fuck your mom they say this
teacher - "omg hi!!! I missed you how were you?"
her friend - "ur mom"