From the French television program Numero Un in December 1969. Most people think this song originates with The Muppets or Sesame Street, but it’s actually from a film called Sweden: Heaven and Hell, a racy “mondo” documentary which has scenes of swingers parties, nude beaches, porn films and lesbian nightclubs. The song was written by the great Italian cinema composer Piero Umiliani.

As I recall “Mah Nà Mah Nà” accompanied the nude beach scene. In that context, the tune takes on a comic “leering” quality.
 

 
Via our friends at Modcinema