Pip-eye, Pup-eye, Poop-eye an' Peep-eye (1942)
Popeye's 4 newphews try to sneak out instead of eating their spinach, so Popeye demonstrates some of the benefits: playing piano, dancing, shadow boxing but each is met with "but we don't like spinach." Finally, Popeye spanks them, and they start eating their spinach. After which, they play the pian