Shooting Water Slugs
When you’re trapped in a tin can for lengthy periods of time, it’s no surprise that you have time to come up with stupid and amusing pranks. Every week, submarines practice torpedo launching procedures.
They pump air into the torpedo tube and “fire” it into the sea. This is when water slugs are “shot.” Sailors who aren’t aware of this odd name frequently have to go down to the engine room and bring a pail of water slugs.