The hand warmer 9000 is a version of a hand job where instead of just the motion of a normal hand job, someone increases speed and pressure of their grip until the male penis begins to heat up and turn red do to the friction caused by the speed and pressure of someone’s hand in the vertical up and down motion.
Fingering or giving a hand job to someone by putting your hand down the back of their pants while they are sitting, far enough to where the hand extends to or beyond the crotch on the other side.
While sitting in the stands at the Bills game, I gave my girl a Buffalo Hand Warmer, because we're classy like that.