A collector of the quim.
Shirley's quim was soaking wet, and so Nigel decided to don the act of the quim bandit in order to win himself a lumpkin.
A: Go eat some quim you fucking quim.
B: I ain't know muhfucking quim bandit.
Someone who draws quim matter from one female, then proceeds to finger another girl in a sneaky exchange of quim juice.
The females are unaware that the exchange has taken place, and may possibly never find out until upon receiving positive results from an STI test.
Note: Even better if the banditry victims are best friends.
'Were you a quim bandit last night?'
'Yeah, slipped it up the fit one first, then her butters mate!'
'Wash your hands in between?'
'Na, i was a right QUIM BANDIT!!'
(possibly ending the conversation with a smell of the quim bandit's fingers)