The family dog warns Tom not to make any noise so he can take a nap. Jerry hears this and immediately devises plans to ensure that the dog's nap will be interrupted.
Editing
Razor-sharp comedic timing that defined the genre.
Practical Effects
Hand-drawn animation with physics that still slap.
Sound
Spike's snoring as narrative device—chef's kiss.

Director
William Hanna
Trivia, insights & behind the scenes
This short won the 1945 Academy Award for Best Short Subject (Cartoons), beating out four other MGM cartoons including another Tom and Jerry.
Hanna and Barbera perfected the 'triangle of conflict' here—two antagonists united only in suffering under a third party's arbitrary rules, a structure they'd revisit constantly.