I was interested to read in your news letter that POSH was once a term for a British halfpenny.
Spotlight has a way of doing that.
As for tosheroon , its etymology isn't know with certainty. That seems the only surefire method to get one's point across the first time. The term was so common that I'm sure it appeared in print before 1980. However, the OED is not as good with American English as it is with British English. Several years ago the manufacturer of a popular denture cleaner ran an ad on TV showing the alleged superiority of its product.