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)
mub is bum backwards
boasting to a friend :"I leapt out and gave him the mub, he was discusted".
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