Rumpy pumpy

The rhyming couplet, rump pumpy, is jocular British slang for sexual intercourse, and dates from the late 1960s. It is not known who actually coined the expression, but it might have been inspired by a character from BBC's radio series Round the Horne, which was popular in the late 1960s. Kenneth Williams played a character called Rambling Syd Rumpo in the radio series, who sang lewd songs full of sexual innuendo, the same sexual innuendo that is present in rumpy pumpy, which, of course, is built upon the words rump and pump, which do not leave very much to the imagination.