dated slang A nickname for the side cap (a foldable military cap also known as a garrison cap or flight cap) worn by members of the Unites States Navy or Marine Corps. Sometimes hyphenated. Primarily heard in US. I asked my grandpa what the funny little hat was called in his pictures from the war, and he said it was his piss cutter. We all tucked out piss-cutters into our belts as we entered the room.