It started with a whimsical little book that became a movie, years before Disney came up with "Freaky Friday".
Turnabout is based on a 1931 book, which had previously begat a 1940 feature film, also entitled, "Turnabout". Like "Freaky Friday", the concept is based on two people swapping bodies, thanks to magic.
Rather than try to explain it, I'll just show the video, uploaded by Gilmore Box. Sterling Holloway (the voice of Winnie The Pooh at the time) is the narrator.
To think that this came out the same year that John Schuck (ex-McMillian & Wife, Holmes & Yoyo) would don the makeup of the Monster of Frankenstein for the first time, leading to The Munsters Today, which would bow a decade later, for a Halloween special that we recently reviewed over at Saturday Morning Archives. Sharon Gless (ex-Switch) would bounce back a couple of years later with Cagney & Lacey, and was last seen on Burn Notice. Turnabout was cancelled after 7 episodes due to poor ratings. To the layman, it seemed as though Universal, which packaged the series, was trying to rip off Disney, but that's not so. It just happened that the original "Freaky Friday", with Jodie Foster, came out 3 years before this show, and was still fresh in some folks' minds.