Little Cheeser is a MGM Happy Harmonies cartoon, released in 1936.
Cheeser the mouse doesn't want to go to bed. In a fitful sleep, he has good and bad "angels" to help him decide right from wrong. The "good angel" (on one shoulder) teaches Cheeser to smoke and drink, while the "bad angel" (on the other shoulder) tries to prevent this. Cheeser attempts to smoke a pipe, look at girlie magazines and do other bad things before realizing that good overpowers evil.
When the good angel intervenes, a war of the spirits ensues. After being chased by a cat, Cheeser is finally exhausted by his journey into the terrifying world of free will. He runs back to bed, says his prayers, and falls to sleep like a good little mouse.