Top definition
The act of being overly nice and polite to the parents of friends/acquaintances, especially mothers, when you are in fact brash and filthy around your peers.

See also: dad spooner, granny grinder
We needed to leave but Kevin was busy being a mum bummer and we got there ten minutes late.

I'm wasn't mum bumming, she was just asking me all these questions.
by barkbat October 22, 2009
Mug icon

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug