Thumbsy-Bump Share definition Flag When you and a bro each stick their thumb up their ass and bump knuckles while turned backwards Me and and the bros always thumbsy-bump at the end of a party. Last night me and kyle did a frontwards thumbsy-bump, our dicks touched but no homo. Thumbsy-Bump by Thumbsy-bumper June 19, 2019 0 0 Get merch Get the Thumbsy-Bump mug. Buy Now — $32.95 See more merch