Backswash 

The process of dragging the back of the hand from scrotum to belly button as a form of sexual gradification.

My wife of 40 years surprised me when during intimacy she backswashed my whole scrotum with her knuckles.

Backswash by Larni Brian-Burns January 30, 2020

Koopa-Backdash-Wave-Slide-Hover-Walk-Moon-Landing 

In Super Smash Bros. Melee, characters who's walk-acceleration is lower than their traction value after wavelanding backwards can buffer a slight walk forwards to decrease the momentum lost. The walk input must be at its lowest value to perfectly execute the tech. (rough translation of inputs) Characters with low traction (Luigi) benefit worse than those with higher traction values in Melee. (i.e Gannondorf can benefit from the Koopa Backdash Wave Slide Hover Walk Moon Landing more than Luigi in terms of distance)
Youtube has more info on this.

The Koopa-Backdash-Wave-Slide-Hover-Walk-Moon-Landing can make virtually anyone feel like they are playing on ice.

Koopa-Backdash-Wave-Slide-Hover-Walk-Moon-Landing by Do_mmar September 11, 2020

korean backdash 

An advanced defensive meneuver created by the Chaiwanese. This technique requires a person to dip their head and shoulders while stepping backwards to avoid being physically hurt. Often done multiple times in succession.

Aris flew into a hotdog fueled rage after his attacks were thwarted by a masterful dance of korean backdashes.

korean backdash by vicnuggets May 30, 2018

karmic backlash

When things go smoothly for a period of time and you're enjoying life, karma finds its way back to you and fucks things up.

I had the best November but I'm getting karmic backlash and December is turning out to be such a drag.

karmic backlash by Yana TV January 21, 2009

backsplash 

the water that sprays upwards from a toilet when you shit too hard

I knew that guy shits bricks...when he came out of the toilet he got backsplashed so bad he looked like he had a shower

backsplash by krak ho August 18, 2003

Blackwash 

When an established character is turned black for no reason other than to diversify the cast. It is the opposite of whitewashing, and is normally not ever complained about

Person 1: Why did they have to blackwash Domino in the new Deadpool movie?
Person 2: What, are you saying she can't be black? You're so racist for not giving black actresses a chance
Person 1: it's not about being racist, it's about being accurate, jackass

Blackwash by Moo024681012 September 16, 2017

Backwash Cum

When you suck a guys dick, and you hold the cum in your mouth and then exchange it back to him through a kiss.

Damn that backwash cum tasted so good after last night.

Backwash Cum by 0dharpsand0flats November 27, 2019