For our British friends, What is a "ring pipe?"?

I think it’s a slang or vulgar word but I gotta know. Once on a TV show there was a live camera that was recording a traffic stop in London or some town I forget where. The driver was abso-fucking-lutley livid with this situation and was really upset because of it being on tape. He told the camera man (looking right into the lens) to shut that F,ing camera off or he was going to cram it in his ringpipe. What did that mean?