to rub your hand up the crease of your buttocks and around your anus, then ambushing an unsuspecting victim with the same hand ih their face (whilst shouting 'mub' at them)
Abbreviation for "Messed Up Bitch"
Definition: (noun) Referring to girls or girly guys who are used to debauched life such as drinking, doing drugs, and getting laid or have absolutely lost a sense of morale
She's a MUB! She's now going out his ex-boyfriend's father.