The solid twatting of a ho's face by the bulbous bell-end belonging to an erect nob. It is either an act of intense passion and loving for the mushroomed one, or an act of anger at the dislike of an unagreeable technique used during oral sex. If the face is struck hard enough with the familiar mushroom shape of said bell-end, then a bruise will be left (see mushroom welt).
"Man that hussy was a fine piece of ass, but when she started using teeth down there, I had to pull out and give her a stern mushrooming."
ayon kay Mo'$ the 2nd ika-30 ng Mayo, 2005