Who said "Say, that's a keen idea!"?

This quote is attributed to Mickey Mouse.

Say, that's a keen idea! - Mickey Mouse

"Say, that's a keen idea!"

Mickey Mouse Creativity

"Hot dog!"

"Oh boy!"

"Gosh!"

"That's swell!"

"When life gives you lemons, make something beautiful."

"Creativity knows no bounds."

"Creativity is the expression of the soul."

"I'm making this up as I go."