Somewhere in the 2000s while Noggin was airing "Play With Me Sesame", there was a segment
that was seen with Grover and Prairie Dawn singing and dancing to an old Sesame Street sketch from 1969 "Mahna Mahna".
Strangely enough, when Noggin stopped airing the show in September of 2007, it just vanished. There was never a re-run on PBS Kids Sprout nor was it released on DVD. The only evidence we have of it, is the remaining screenshots of the segment.
Update: This segment is found [1]