This video from early 1975 from the Sonny and Cher show with the Osmonds has to be the most 70s thing ever. OMG those costumes. This also was a precursor of things to come. Right after this Donny and Marie got their own variety show. Then the Bradys appeared on the Donny and Marie show and then the Brady Bunch got their own variety show too.
Long live the 70s and the variety shows
https://www.youtube.com/watch?v=R6FIVEUld4U