Just because it's history doesn't make it true

Wikipedia says of Thomas Crapper:

It has often been claimed in popular culture that the slang term for human bodily waste, crap, originated with Thomas Crapper because of his association with lavatories. A common version of this story is that American servicemen stationed in England during World War Isaw his name on cisterns and used it as army slang, i.e. "I'm going to the crapper".^[10]

The word crap is actually of Middle English origin and predates its application to bodily waste. Its most likely etymological origin is a combination of two older words, the Dutch word krappen: to pluck off, cut off, or separate; and the Old French crappe: siftings, waste or rejected matter (from the medieval Latin crappa, chaff). In English, it was used to refer to chaff, and also to weeds or other rubbish. Its first application to bodily waste, according to the Oxford English Dictionary, appeared in 1846 under a reference to a crapping ken, or a privy, where ken means a house.

.....

Rico says just because it sounds definitive doesn't make it so. Having once used an original Thomas Crapper toilet, located in the lighthouse in the Marin Headlands state park in California, Rico says the rim of the toilet, made from cast iron in the Victorian manner, had raised lettering noting the name and address of the manufacturer. When the wooden seat was lowered, however, the only letters, visible through the gap at the front, was 'crap'...