Our sub was on station somewhere in the Pacific, and I was standing AEA watch. One of the things we do as AEA while on station is to man the Time-Range plot in Control, a job that requires me to endlessly record every fishing vessel and whale that happens to cross our sonar. The night watch was going very slowly, so we decided to take advantage of the free time to start on housekeeping routines a bit early. The COW called the forward auxiliaryman (A-ganger) to line up sanitary tanks 1 and 2 to blow overboard. He never actually stated to blow them overboard - and for good reason, we were still at "400" feet. This apparently was missed by the mechanic (we were all pretty out of it), and he dutifully went below to the 18-man berthing compartment to accomplish his task.
About five minutes later, those of us in Control began to hear a strange hissing noise, followed by a rather sharp pop and a much louder hiss. The COW and OOD were quick to make a 1MC - "Report the source of the abnormal noise to Control". We needed no report. About ten seconds later we began to smell what could only be described as the most foul sewage ever known to man. It was quickly decided to handle this as a legitimate casualty, as we were all becoming nauseous from the smell, and the officers were concerned about the crew becoming completely overcome by the odor.
We all donned EAB's and waited as reports began to filter in, and the truth of the casualty became clear. The A-ganger had lined up SAN2 to blow overboard, but forgot to wait for the boat to come to PD. He pressurized the tank and began blowing overboard, unfortunately, he did not notice that the pressure was much higher this time due to the ship's depth. Well, the pressure gauge for this tank happens to be in one of the bunks (occupied by one of the ship's cooks) and it was the source of the 'pop' we all heard. When that gauge let go, the bunk (and the cook) were instantly covered in our forgotten meals. The A-ganger quickly isolated the hull valves, but there wasn't much he could do about the influx of crap that was blowing all over the berthing compartment. Men fell out of their bunks and ran for their lives, and the mechanic jumped into the bunk with the broken gauge and tried to plug the leak, to no avail.
When it was all over, and believe me - it was, the ship was emergency ventilated, and a decontamination area (fit to make any Radcon officer proud) was established in the torpedo room. We went through a couple dozen tetanus shots for those directly exposed to the mess. Needless to say, we were all hot-racking afterwards, as the mattresses in the berthing area were unfit to sleep on, not that anyone really wanted anywhere near the stubbornly lingering odor.