french biscuit Share definition Flag A small, moist, perfectly-formed turd. Possible origin: cockney rhyming slang with the word "shit". "I'm proud of that french biscuit I layed earlier", or "Watch out, or I'll lay a french biscuit on your desk" french biscuit by Captain Bird's Eye July 30, 2008 0 0 Get merch Get the french biscuit mug. Buy Now — $32.95 See more merch