a phrase you use when you have no good comebacks.
"you are an ugly ass"
"Ur mum"
ur mum is what people say when they don't want to say an actual answer.
I had passionate sex with ur mum last night.
Friend 1: What day is it?
Friend 2: ur mum
basically every young kids say to people as a joke
"what the fuck are you looking at" "your mum"
1- “holy shit, whats that big fat monster?”
2- “what?? where?”
1- “oh. its just ur mum”