Und-Diving

The act of engaging in sexual activity with a obese member of the opposite or same sex.

Origin
The name of a escape method used by a man or woman following a sexual encounter with an obese member of the opposite, or same, sex that involves using the larger than average size underpants of the subject as a parachute when jumping from the subjects bedroom window.

I met a really nice girls last week at the party and ended up Und-Diving the next morning