Butt-piping 

The act of two individuals bending their penis straight down and having butt sex with each other at the same time.

Joe laid down on his stomach and Dante laid down on his back. As soon as they were hard, they pointed are dicks down between our legs and began butt-piping each other.

We could have won that round of search & destroy but Joel and Christan were too busy butt-piping each other in that building.

Butt-piping by Palsy Chef April 7, 2011

butt pimping 

The action of one hand staying level and straight out while the other hand continually 'pumps' the ass. Commonly used on strippers in order to give proper lovings.

Hey bra, lemme give your gf some butt pimping.
nah dude she's taken and not a stripper

butt pimping by An observant human being, November 2, 2014