I figure that since the majority of people working at McDonald's now are high school students, and we all know that High School students are prone to break out into song about anything, these gentlemen (who were very happy at mopping and cleaning out grease traps) must be the closest thing the 70s had to High School Musical... expect Fame.
Dr. Suess' only live action film - The 5000 Fingers of Dr. T. I didn't see this film until my 20s, but wow did it amaze me even then. The sets are design marvels. The musical numbers and acting are certainly of a time and place, but fine for a kid's film. And that said, most young kids would not appreciate what trip this film is. It's surreal.
Hans Conreid (known for dozens of cartoon voices, and dozens of appearances on 70's sitcoms) plays Dr. Terwilliker who's goal is to open a piano academy with 500 captive boys playing his uber piano. He locks all other musicians in his dungeon.
The above scene has the Dr. and the Handyman (who's decided to assist our young protagonist) in a Hypnotic Duel.
If you like musicals, Dr. Suess, or just need a good film to trip to this summer, see if you can find a copy of the 5000 Fingers of Dr. T.