gum shut Share definition Flag The post-copulating effect of hardened ejaculate, causing the urethra to become clogged. Dude, I fucked some bitch last night and this morning I couldn't hit the toilet and pissed all over the floor from being so gum shut. gum shut by Willis Corona July 31, 2007 0 0 Get merch Get the gum shut mug. Buy Now â $32.95 See more merch