water hammer

Something engineers, mainly Machinist Mates, do in the U.S. Navy to each other in the boiler/engineering room. A container of water is dumped from an upper level area to someone on the lower level, or from any high area to any lower area. It is always meant to be a surprise. It is also done to people who are sleeping on watch as a way to wake them up, and they do so in shock, to teach them to not sleep on watch or else it will happen again. It is also done to people who are already awake as a practical joke. Something like that would usually never be done to any higher-ups, especially those that don't participate in the game, since it will get you in trouble.

When an industrial facility that consumes a copious volume of water suddenly stops drawing water from a water treatment plant via a pneumatic switch or quick-close valve. The instantaneous closing of the valve causes a backup of water pressure that breaks water treatment plant pumps and pipes.

It’s like surge and swab...but different because it’s in reverse...