Big-Girl Clothes, Powder and Rouge

Minnie Mouse donned those items in anticipation of her first meeting with Walt Disney back in 1928.  That's according to a back cover feature in Walt Disney Comics and Stories issue #10 published in July of 1941.

The text of the article:

Away back in 1928, Minnie Mouse decided to get a job and help support her family. She read that Hollywood's newest producer, Walt Disney, had just signed a new star, Mickey Mouse, and was looking for a leading lady to play in a wonderful picture to be called "Gallopin' Gaucho."

Minnie wanted that job. She wanted it so badly that she dressed up in big-girl clothes, put powder and rouge on her face, and went to see Walt.

"Minnie," said Walt at the interview, "I have a feeling that underneath your gaudy get-up there beats the heart of a sweet, lovable little girl.  If I could be sure of that, I'd give you the job."

A tear rolled out of Minnie's bright eye.  She told Walt that he was right, and explained to him that it was only because she wanted so much to help her family, that she had tried to appear grown-up and sophisticated.
 

Walt signed her immediately and she and Mickey made "Gallopin' Gaucho." After that, they were so, busy making pictures for Wait that they haven't had time, to this very day, to catch their breath.  Sometime soon, though, they may take a vacation, and if appearances mean anything, there will be wedding bells for Mickey and Minnie Mouse.

You can study Disney history for years upon years, and still manage to learn something new everyday.