So apparently, Jim Henson was covertly introducing us to porn at a very young age. My sources are telling me that the "Mahna Mahna" song was from a Swedish porno from the 60's

I"m just as dumbfounded as beaker. And if in fact this is a Swedish porn flick, that answers a lot of questions about why the Swedish Chef was on the show.
Here's the clip from the film...