Big John/ Little John was a Saturday morning kid’s show on CBS that ran for one season in 1976. Sherwood Schwartz of Gilligan’s Island and The Brady Bunch was executive producer. The premise was that Herb Edelman accidentally drinks some water from the Fountain of Youth in Florida by accident, and then…at highly inopportune moments, gets younger and younger and younger until for some reason he winds up as blond, straight-haired Robby Rist (best remembered today as “Oliver” on The Brady Bunch.) The credit sequence here sets it all up for you.
Big John, Little John