This isn't quite how I remember Rainbow ...
Rainbow was a kids TV program that ran during the 70s and 80s. It featured Geoffrey, Bungle, Zippy and George and a few random others. It certainly wasn't my favourite program, but I must've watched a fair bit of it over the years.
But this isn't quite how I remember it from my childhood:
Some people out there on the interwebs seem to think this is evidence that children's TV is and always was filthy and smutty and we kids used to be just too innocent to notice, but it's not true. They filmed this for a BBC christmas party special - it was for internal use only. I bet they had a blast doing it, but I marvel at how they could keep straight faces through it.