People use this as a joke as making fun of people's mothers by simply saying ur mum
"Yo I banged ur mum last night"
1- “holy shit, whats that big fat monster?”
2- “what?? where?”
1- “oh. its just ur mum”
basically every young kids say to people as a joke
"what the fuck are you looking at" "your mum"
The ultimate insult to destroy your enemies weaknesses: no u
Fred: ur gay
Bob: do you know who else is?
Fred: no
Bob: ur mum
Fred: (gets sniped)
a joke that 12-year-old boys use, and they think they're funny.
'ur mum'
nothing else, just ur mum