0 used to describe something such as an organization, machine, or course of study that you think is not as good or serious as it should be: --
He works for some Mickey Mouse outfit (= company) in Oklahoma.
1 (of an organization, place, object, or activity) too small and simple; not to be taken seriously: --
I don’t get paid enough to put up with that Mickey Mouse sort of stuff.
NYA ORD
European
May 10, 2021
DAGENS ORD
Shimmer
Mickey Mouse