Masturbating in a way that where your hand slaps and or slapping your scrotum while stroking down to make a smacking noise.
My friend and I had a fapturbating contest we wanted to see who could do it louder before teachers outside the bathroom could hear us. When we fapturbate our scrotums get so red from the smacking.
by Scrotum Slayer March 24, 2018
by BFFN July 12, 2009