1) when you shape your finger like a gun and go
bang bang!
2) the name of the boy band Stan, Kyle,
Cartman & Kenny made that
Wendy joined
3) to pleasure a woman with your hands in her pussy or ass or even to a man via the ass
Cactus Jack's signiture taunt was to finger bang and say "Bang, Bang".
"I'm gonna finger bang, bang you all through the night. I'm gonna finger bang, bang into my life.
I
finger banged Michelle last night. She obviously liked it cause she
giggled and moaned during it.