A tattoo made by kids while in school. Usually this is done when classes get too boring for anyone to stand it. School tattoos are made with any objects that can be found in school. Usually done with a staple and ink from a broken open pen.
Kid 1: Shit man, look at this School Tattoo I did in math class!
Kid 2: Cool man, but what the fuck is it?
Kid 1: Its a picture of the teacher; look closer.
Kid 2: Oh, I see. That ugly fuck.