Wikipedia

Ah, Thomas Crapper. He's the hilariously named inventor of the flushing toilet, right? Wrong! Crapper's crapper is one of the world's most famous potties, but incorrectly so. While Thomas Crapper did not invent the flushing toilet, he did much to increase its popularity and developed some important related inventions, such as the ball cock (an automatic valve). The word crap doesn't even come from his name; it is actually of Middle English origin and first appeared in the Oxford English Dictionary in 1846 under a reference to a crapping ken, or privy. As Thomas Crapper launched his company in 1861, there is no direct link between his name and the colloquialism.

See a brief history of toilets.

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