The Aristo-cat

The Aristo-Cat is a 1943 cartoon directed by Chuck Jones. It features the debut of Hubie and Bertie.

Storyline
Meadows, a butler is tired of the constant practical jokes of the family cat, Pussy, so much that he decides to quit his own job. The cat doesn't know what a mouse looks like, so when Hubie and Bertie show up, he get's terrified. At the end, the main problem was revealed to be a dream.