Jaw-strength training is where you put random items in your mouth and chew them from boredom. But somehow in the end, leaves your jaw hurting like you just ate out a humongous pussy.
Joe : "Chris, why are you not eating my asshole out aggressively tonight?"
Chris : "Sorry Joe, I had a tough jaw-strength training session earlier"
Joe : "Oh well let me suck your dick then."
Oh boy, I feel like I just ate a humongous pussy out. Must have been the jaw-strength training.