tummy knuckle 

the very center of a persons' abs (more common when it's a 4 pack) that is harder than the rest of that abs, and tightens similar to a knuckle. It hurts when hit directly, similar to the pain of playing bloody knuckles.

(out of stupidity) I'm going to break your tummy knuckle!

My tummy knuckle hurts after doing so many crunches.

tummy knuckle by Aaron Moe Scott March 31, 2010

swiss knuckle

penetrating an anus with your unusually long knuckle

perry: dude how'd it go with sherry last night
terry: it was awesome dude. i got to swiss knuckle her
perry: aw dude, gross. we didn't shake hands did we?

swiss knuckle by dry heaves January 15, 2011

walrus knuckle 

Camel toe for fat women

Her full body showed her walrus knuckle through her tight pants.

walrus knuckle by Charlie67 September 21, 2013

Moose Knuckle Buckle 

When you punch someone in the balls and ass at the same time

I just gave that fool a moose knuckle buckle

Moose Knuckle Buckle by Cobs sammitch October 20, 2016

Pink Knuckle 

A ragingly, engorged clitoris.

She was so horny her pink knuckle was all swole up.

I was stroking Rachel’s pink knuckle last night. She was squirming and squirting.

Pink Knuckle by Eaton Holgoode October 9, 2018

Ukrainian knuckle duster 

A sex position in which you double fist a woman with your wrists together, while squatting over her and slamming your hands inside the woman's cooch like an oil well.

Sex isn't the same with my wife anymore since she let me whip out the Ukrainian knuckle duster

Ukrainian knuckle duster by turbo_moisture December 8, 2018

Pee Knuckle 

A game where you and a friend sit on the ground across from eachother, with your feet touching. The first to kick the other in the balls first wins.

Me and my brother played Pee Knuckle when I was 7, I'm starting to think that's why I can't have kids now..

Pee Knuckle by Light Refactor May 20, 2019