Mushroom Welt
(See Cocksmack) The welt left by the head of a circumsized cock after a bitch gets out of line when giving you head and needs to get smacked upside her head.
Oh man, it's turns out that bitch was a biter and I had to leave her with a vicious mushroom welt!
mushroom-shaped welt
A mark left on someone's flesh resulting from being slapped by a penis. The impact of thebulbous glans penis and narrower shaft leaves a mark with a shape much like that of the fruiting body of a mushroom.
Your mother wasn't very careful with her teeth when she was sucking my wang, so I pulled my dong out of her mouth and beat her on the face with it, leaving several mushroom-shaped welts that developed into bruises that were clearly visible when she picked you up from school later that day.