In the 1800s, after farming on the same land for hundreds of years, the Europeans would have to fertalize their land. To do so, they sailed to South America to get bat poop. When they got there, they just threw the poop into the bottom of the
boat. On the way back to Europe, the boats would leak(they were made of
wood), and the water and the poop would mix. It would then get really
hot and humid down there, and the boats would catch on
fire and burn in the middle of the ocean. After
people figured out what was happening, they started putting the bat poop in crates. They then stamped S.H.I.T. on it. S.H.I.T. stood for ship high in transit. Hence the word shit.