knuckle knock
A synonym for "fist bump."
Seeing a teacher knuckle knock his students on the last day of class nauseated me.
Knock Knuckles
The act of simultaniously donkey punching and anal fisting a female sexual partner. Each hand goes in far enough that they can knock the knuckles of the corresponding fist. An additional partner can be used if desired.
Yo, that bitch is so kinky, she let me knock knuckles last night!
Knuckle Knocking
When two women vigorously scissor.
“Eating a combo of oysters & chocolate always has me in the mood for knuckle knocking.”