The reason why toilets are sometimes called “crappers” has its roots in World War II and American soldiers bringing back slang terms from their time overseas. Simon Whistler explains the origin of “crappers” and also why toilets are sometimes called “Johns” in an enlightening episode of his series Today I Found Out.
It all started with U.S. soldiers stationed in England during WWI. The toilets in England at the time were predominately made by the company “Thomas Crapper & Co Ltd”, with the company’s name appearing on the toilets. The soldiers took to calling toilets “The Crapper” and brought that slang term for the toilet back with them to the United States.
In the video Whistler also mentions his other channel TopTenz where he recently presented a list of ten things that have not changed in the last 100 years, including the toilet.