slip jack 

a face that looks like it was under a car when the jack slipped

there goes 'slip jack' the ugly barstard

slip jack by buckshelford October 19, 2005

Peanut Butter Slip Jack 

The act of having your girl lick a generous helping of peanut butter off your junk, leaving behind a tacky lubricant. You then slam your dick into the first available hole and jackhammer it like an old sidewalk.

She walked funny for days after I gave her the Peanut Butter Slip Jack.

Peanut Butter Slip Jack by The Cum Factory June 28, 2011

Slip 'N Jack

You and your girl are in the shower, and you don't really have much room to move around. So you both sit down facing each other. Her legs go over yours and you're sitting with your genitals next to each other. You take your dick and put it in her pussy. Then you proceed to move your dick with your hand in a jacking off motion in her pussy. Hence the Slip 'N Jack.

Mostly used in the shower, but also possible in a hot tub or a pool where you can't move much. Slip 'N Jack

Slip 'N Jack by Scruffs June 20, 2009

Slipjack 

A prison term for placing ones weiner between another males lubed butt cheeks, squeezing them together like boobs amd proceeding to hump vigorously. Also know as the bro slide if you're not incarcerated

Ron
Man this prison shit is for the birds. I almost wish I was gay.

Phil
I have a way we can do it and not be gay. It's called the slipjack. You want to give it a shot?

Ron
Hell yes! I've been wanting to slipjack them cheeks for a year already! Let's get it on!

Slipjack by SnowmanND December 18, 2018