“Knowledgeuity”reports that no one named John P. Crapper invented the flush toilet. But there was a man named Thomas Crapper who made a lot of improvements to the flush toilet, more than two centuries after it was invented. He is best known for improving the flush toilet and its parts and contributing to the improvement of modern indoor plumbing. In addition, the name of the inventors of the toilet seems to be inextricably linked with the English word for toilet. Such as "using the John" and "crap."

So who invented the flush toilet? From this we also find the origin of the English expression for toilet. The original flush toilet was actually invented by an Englishman, Sir John Harington, in 1596, and this is where the idiomatic expression "I need to use the John" is thought to have originated. He invented the first flush toilet and installed it in Queen Elizabeth I's palace.

But the foul smell from the sewers was a problem Sir John could never solve. Alexander Cumming designed and patented the "S-type trap" in 1775, which formed a bend in the sewer pipe that retained some water in the pipe to prevent foul-smelling gases from entering the room.Then, in 1778, a man named Joseph Bramah invented the first practical flush toilet.

So where do the phrases "I need to use the John" and "Crap"  come from? Many people mistook the inventor of the toilet was a man named John P. Crapper, giving rise to the myth that his name is the origin of the English expression. The initial of his middle name, "P," was interpreted as "Produce," which in this case meant Produce.

John Crapper is supposed to be a fictitious name, but not quite.The name was probably inspired by the name Thomas Clapper. The word crap actually comes from Middle English as a reference to garbage or chaff, but the meaning of human excrement comes from two earlier words, including the Dutch krappen, meaning to cut off, and the Old French crappe, meaning waste or rejected material.

Thomas Crapper (1836-1910) made improvements to the flush toilet, including the "float cock" and the "U-bend"， which were incorporated into the toilets sold by his company. During World War II, many American soldiers stationed in England called The toilet "The Crapper" because The company's logo was on The toilet they made. When the war was over, soldiers came back to the United States and brought the name back with them. Today, the company's name, engraved on the manhole cover at London's Westminster Abbey, is a relatively niche tourist attraction.

However, these English toilet expressions are rude and are not recommended. For example, "I have to go to the bathroom" can be used in any place, or friends can say "I need to take a leak".