When two guys fuck one girls pussy at the same time, while coordinating their thrusting such that when one is moving in, the other is moving out; thus simulating the piston action of a V-Twin motorcycle engine. If the timing is not correct it only qualifies as a DV. It is recommended that only good friends attempt this because getting the timing right can be tricky.
Did you and Dave V-Twin that slut from last night?
No, that motherfucker doesn't have any rhythm. We just gave her a DV.