Cutting open black-water suction pipes in the ship's Mini-Laundry (FRE and MON during MLR) and plugging the same section of pipe with threaded rod and welding rod respectively. Then welding the pipe back into place, thus blocking all of the black water suction in the forward end of the ship.
Cutting the AHWCS cables and tucking the cut ends back into the wiring bundle in the wire-way. We had to use a TDR (Time Domain Reflexometer) to measure how far down the cable the cut was.
Every ship in the fleet loses brass fittings. At one point, we had 2 ships in a row come back requiring all fire-hoses to be replaced because someone cut off the hose ends in the racks. 39 hose stations, 4 hoses per station, that's nearly 160 fire hoses needing replacement. Not to mention the lazy rod covers that went missing on a couple of ships, the brass bulkhead number markers...and so on. The fire sentries from ISI using our extinguishers, and keeping them.
Failing to put up a heated enclosure around the SONAR transducers when the dome had been removed, resulting in them freezing, the rubber separating from the crystal, and having to replace over 10% of the SET's.
The list goes on...