Jacking Black 

The act of masturbating whilst really high so that when you jizz all the blood rushes from your head and you black out. May be hard to achieve.

Also called Knocking Off.

X: "Ben and I tried Jacking Black last night"

Y: "No Way! You guys are crazy! Any success?"

X: "Yep, I totally Jacked Black!! Ben didn't manage to though. It really isn't easy!"

Jacking Black by Jacking it in San Diego April 18, 2015

Back jackin'

(băk'jăkin') v.- An approved method of masturbation in the workplace in which you use the upper posterior side of a willing co-worker to rub your genitals on in a slow, sensual motion. Grunting noises are an optional way of showing approval in your back jackee, but can make for awkward moments.

Chris, noticing Curt's lusting gaze at his boner, decided a back jackin' was imminent.

Back jackin' by boner gazers March 4, 2009