when you take your wang to someone's face with great force(mushroom slap), leaving a mark that looks like a mushroom (because the end of your penis kida looks like a mushroom)
whiping ones partner with you penis (Piece, Wang, Schlongect)
"That bitch said she wanted a tattoo so beeing the gentelman i am, i whipped my cock out and gave her the old mushroom tatoo, after that she soon changed her mind
By Eileen
Mushroom Tatoo
when i smacked gina in the face with my dick and left a imprint of my bell end on her face