Goo gun Share definition Flag Goo Gun; n. The male genitalia, so named for its ability to eject bodily fluids. Chicho "How did it go last night?" Joe "I assaulted her with my goo gun!" Goo gun by Joe Henkelman September 30, 2006 0 0 Get merch Get the Goo gun mug. Buy Now — $32.95 See more merch