bumping knuckles 

Fist fighting. Professional, Amateur or Street.

When two dudes get to jawing in the Club, then go outside...'bout to be some "bumping knuckles!"

bumping knuckles by talk2me-JCH2 March 5, 2021

Knuckle Bumping the Oatmeal 

When you fist a loose bitch with a yeast infection.

Wallace- Dude, you took her home last night? She's a no-go with that YI.
Jones- Nah man. I was knuckle bumping the oatmeal all night.
Wallace- You're fucking sick.

Knuckle Bumping the Oatmeal by Kiril Ishikawa May 25, 2015