You've Got to Eat Your Vegetables!!
You've Got to Eat Your Vegetables!! was composed by Bobby Prince originally for the game Commander Keen: Keen Dreams (DOS), but it never ended up being released with the game. The developers of Keen Dreams, id Software, had written the game with the music as a backdrop to the game's introduction. However, the game's publisher, Softdisk, wanted the entire game to fit on a single 360 KB floppy disk, so id Software had to remove the music.
The origin of You've Got to Eat Your Vegetables!! is revealed by Bobby Prince:
Thankfully, this song did eventually see the light when the next Keen game, Commander Keen IV: Secret of the Oracle (DOS), was released. It was used as background music for the levels: Sand Yego, Miragia, Lifewater Oasis (on the first screenshot above), and Well of Wishes (on the screenshot below). The songs carry no internal titles, but was named "veggies" in the archive by John Romero. Bobby Prince released an upgraded MIDI of it with the name, "You've Got to Eat Your Vegetables". Later he contacted the site and revealed that the proper title also had two exclamation marks at the end.
Bobby Prince even created lyrics for the song that would be seen as dialog between Billy and his mother, father, and sister. They are below with some notes.
[Billy's mother says in that muted trumpet style of her's:] You've got to eat your vegetables! Can you hear me? You've got to eat your vegetables! Tell him father. [Then Billy's dad, in his muted bass trumpet voice says:] You've got to eat your vegetables. NOW! [But, worst of all, then comes this tiny, high-pitched muted trumpet voice of the little sister:] You've got to eat your vegetables! Nyah nyah nyah nyah nyaaaah nyaaah!
- youtube.com/watch?v=tkCPK2m7D-8 - Bobby Prince explaining the song's origin.