When defecating, the biggest, most awesomely large dump that you haven't had in a good long time. Usually arises from not crapping for more than 48 hours or when coming off of constipation. Called so because the waste is so big, it's like a nuclear submarine trying to leave the bowels, which is a very large submarine. An atomic dump.
Today I went over Memere's house and launched a nuclear submarine.
Try as he might, the nuclear submarine deep in Gorby's colon wouldn't come free, until he had some Taco Bell and it was launched in the public restroom.