What is blue mushroom?

The act of gripping an erect penis by the shaft right below the head and punching the penis until it is completely bruised.

I was with this guy last night and he totally wanted me to blue mushroom him!

blue mushroom - video

Blue mushroom - what is it?

see also mushroom bruise and mushroom tatoo. It is the mark on a woman(or man), after being whipped by an erect penis.

did you see the mark on her face?, that must've been a blue mushroom