Mama Cass Elliot and Carole Burnett
I recall the first time I saw this over 40 years ago on the Carol Burnett show. I was working out of town and alone watching on a black and white tv.
I was blown away. I got up and paced wondering if any of my friends had seen it. I saw this wonderful thing and no one to share it with.
Nowadays you can just email a link but I got a buzz when a friend raved to me about the same performance a few months later.