Definitions by Lifewithaknife

Masturbation Muscle 

When a male has fapped so much, that one arm is bigger than the other one.

Guy 1 "Dude how did Daniel get so buff?"

Guy 2 "Look at his arm."

Guy 2 "It's because he tones his Masturbation Muscle."

Daniel "No! I just workout."

Masturbation Muscle by Lifewithaknife November 1, 2011