nailbutt Share definition Flag a butt in which is made up of rusty nails. kind of hard to explain, you just have to see it for yourself. "i couldnt even sit on the toilet, i have a nailbutt" nailbutt by John Crabs March 31, 2008 0 0 Get merch Get the nailbutt mug. Buy Now — $32.95 See more merch