I'm sure you've all heard that "no word in English rhymes with month, orange, silver, or purple".

Well, I've found one that rhymes with purple, and it's courtesy of Jack Kerouac in chapter 2 of his novel Desolation Angels...

... why ask questions or tear hair or weep, the burple blear purple Lear on his moor of woes ...

There it is: burple. Now I know Jack Kerouac isn't exactly on the same level as Dickens or Shakespeare and he was probably off his face when he wrote the book, but as it's in a book, by a famous author, it must be ;-)

A quick search on Google reveals there was a product in the 80's called a Burple (here and here), though I suspect it was probably only available in the US.