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I just read about the skit that was mentioned on Carol Burnett's page, and I have some raw data to add to it. The wiki says:
A 1970 episode of The Carol Burnett Show also featured a Sesame spoof, "Poppyseed Street", with the cast imitating Big Bird and Oscar the Grouch.
McFarland's Television Variety Shows says:
12/7/70: [Guest stars on this episode are] Don Rickles, [and] Mel Torme. Adult-oriented "Sesame Street" spoof, "Poppyseed Street", with cameos by Lucille Ball, "Mama" Cass Elliot, Ricardo Montalban, Dean Martin, Jim Nabors, and Dick Martin.
There is more on that week's show, but I wrote out the part that's relevant for us. It seems odd that that the Sesame parody featured a bunch of surprise cameos, and not the main guest stars for that week, unless it was pre-taped. Since I'm not sure who exactly was in the sketch, I thought I would leave it here for now. Also, from Googling Poppyseed Street, there seems to have been a score written for it that is now in storage at UCLA, so now I'm wondering if they did any parody songs or any original songs during that number/sketch. It looks like Danny added that information to her page. Maybe this will be a show that we can track down. So make that 5, 5 Sesame references on The Carol Burnett Show! Ah-ah-ah!