backjack 

The act of multiple men sodomising eachother in a human train. Just before ejaculating each one pulls out and blows their load all over the back of the guy in front shouting "twenty-one !"

Damien the sick fuck went out and played backjack with 5 guys he met at a gay bar.

backjack by DamienN July 14, 2006

Backjack 

Verb.

the act of paying someone back in cigarettes for a cigarette bummed earlier.

catherine: hey john, can i bum a cigarette?

john: sure, as long as you backjack me

Backjack by BOBBLE BOO November 8, 2007

Backjack 

A form of masturbation where you slide your hand down your dick with your hand backwards, forefinger and thumb touching eachother. Your thumb should be facing in twards your balls and your pinky out twards the head.
Painting a face on your hand is optional.

"Sometimes I rub one out backjack style to shake things up a bit."

Backjack by Clam Choder May 3, 2007

Backjack 

The act of jacking off your boyfriend whist he is sat behind you as you are typing this onto his laptop at the same time. During this he is sitting on his Nintendo DS playing Pokemon.

Example: having a laptop on your knee; sitting on the end of the bed; penis in hand! There you have, a backjack!

Backjack by Carrots. June 29, 2014

backjack 

the art of bending the penis through the back of the legs for a handjob

she said she was gonna show me something ive never seen before so she pulled my pp through my legs and gave me a backjack

backjack by peepsey April 8, 2008

Dactyl Backjack 

Performing the ol' reach around on yourself, an advanced masturbation technique. Word origins can be traced to dudefuckinghellyeah (DFHY) at burning man 2009.

The stranger is getting old, I think today I'll change things up and pull a dactyl backjack when I'm wanking.

Dactyl Backjack by 1009 September 19, 2009

Canadian Backjack

During Sexual Intercourse, A woman sticks her one of her tits into the mans asshole, and reaches around and jacks you off at the same time.

Man, I jus got Canadian Backjacked.

Canadian Backjack by Dillon Coolman December 11, 2011