mushroom beltbuckle Share definition Flag When you have a boner and you tuck it up against your body and the head of your penis sticks out above your jeans Oh gross!!! I cant see your mushroom beltbuckle!!! mushroom beltbuckle by B.333 July 27, 2011 0 0 Get merch Get the mushroom beltbuckle mug. Buy Now — $32.95 See more merch