Having got used to a tiny black and white TV that took three weeks to warm up and only had two channels when it finally did, seeing giant technicolor (sic) people (and penguins) dance and sing forged an instant love affair with the movies that has stayed with me ever since...
Freaky Friday (the original one). I have indeed surprised myself by remembering that and perhaps even more by remembering the second one was called Diamonds On Wheels. Enjoyed both immensely