Chuppa chup?

While watching the comedy "Absolutely Fabulous" on television last night, we heard one of the characters, who had recently acquired a new boyfriend, talking about doing the "rumpy pumpy"? I know I have led a fairly sheltered life but even I was able to work out that it meant "intimate relations", "making love", "a bit of the old punch in the pants". As we talked about it on the way to the bus stop this morning, my partner said she knew someone who called it something similar, and that this person's mother called it the "chuppa chuppa" - and that chuppa chup was actually a play on that. Not sure if that's actually so, but it's an interesting thought.