jizz-brain Share definition Flag verb. When you're deep throating a betch and you dick goes up instead of down and you ejaculate all up in there brain Oooh I was with James last night and i totally jizz-brained his betch ass. jizz-brain by Matthew The Pimp Fucker June 21, 2007 0 0 Get merch Get the jizz-brain mug. Buy Now — $32.95 See more merch