rust-bone Share definition Flag A rust-bone is the after product (fecese) left on the shaft of a man's penis after engaging in anal sex with a woman Dude! Dont't even get near me. I totally know about the rust-bone your gf gave you last night!! rust-bone by Jonathan Brian January 9, 2008 0 0 Get merch Get the rust-bone mug. Buy Now — $32.95 See more merch