Donald is shoveling the snow off his walk; Chip 'n' Dale are shoveling their branch. Donald tricks them into shoveling his walk. Angered, they sneak into his house, where he's getting ready to make popcorn. They've never seen this before, but they love it. They stow away in the box, then make off with the bowl of popped corn.
Sound
Clarence Nash's Donald scream hits different in mono.

Director
Jack Hannah
Trivia, insights & behind the scenes
Jack Hannah directed 48 Donald Duck shorts and reportedly found Chip 'n Dale his favorite antagonists because their small size let him invent more creative physical comedy.
This short established the 'Chip 'n Dale as chaotic popcorn thieves' template that would define their character for 70+ years of Disney merchandising.