Etymology

The adjective sense developed during the second world war, after a large quantity of low quality counterfeit Mickey Mouse watches flooded the UK.

Proper noun

1. The most famous Disney character, an anthropomorphic mouse.

Adjective

1. Of an item of dubious quality.

   I took Twentieth Century Film, hoping it would be a Mickey Mouse course and an easy A.

Quotations

"They're putting a Mickey-Mouse operation on the ice... It's ruining hockey." - Ice hockey player Wayne Gretzky after his Edmonton Oilers beat the New Jersey Devils 13-4, 1984 (espn.go.com)