Mick Jagger was supposedly having relations with David Bowie right? Actually it was David Bowie and Dennis Weaver so Mick Jagger wrote the song "Get off of McCloud".

I actually heard that Jagger saw. Hugh Heffner having relations with Dennis Weaver (perhaps bored with all the bunnies at home). Hence the lyrics "Hey Hugh, get off of Mc Cloud".

That's probably the real joke. Sounds better too.

Then there's the Scottish farmer version, "Hey Mc Cloud, get off of my ewe!"

Awesome!