Definitions by fuckmesidewaysintheass

japanese jackhammer 

a sex position in which the participant who is riding cowgirl gets tired and so the bottom participant thrusts up against or inside of them. This position often creates awkwardness...

- "Damn I'm sorry I japanese jackhammered you last night."
- "It's okay, I was getting a little tired."

japanese jackhammer by fuckmesidewaysintheass March 2, 2017