when a dude slaps his penis against someone and it leaves a mark like a mushroom.
"You better take that back or I'll give you a mushroom print right across your forhead!"
by ho magnet April 26, 2003
The act of imprinting your penis on a foggy car window.
Adam mushroom printed his window when some girls pulled up beside him.
by XxThanatosxX May 12, 2006