A makeshift cannon for shooting potatoes, usually made from PVC pipe. The two major varieties are pneumatic guns, which rely on compressed air, and combustion guns, in which a flammable chemical such as hair spray is ignited.
Guy at the hardware store: "I love shooting spud guns, just be careful not to blow a hole through your liver".
A derogatory term for a homosexual male. Deriving from the small portions of faeces that can get stuck in the eye of the penis during unprotected anal sex being similar to the portions of potato that get pulled out when a small hand-held Spud Gun is inserted into the potato to 'load' it.