The Vanishing Private (Disney 1942)

The Vanishing Private is a 1942 animated cartoon by the Walt Disney Studios, starring Donald Duck in the World War II years.

Donald does some camouflage painting, painting a cannon. Unfortunately for him, he painted the cannon with yellow, green, and red stripes with black polka-dots. Sergeant Pete explains that the point is to make it so the cannon cant be seen and forces Donald to re-paint it. Donald storms off to the Experimental Laboratory: Camouflage Corps.

Donald found some invisible paint, which he used to paint the cannon. Soon, the cannon became invisible, as the Sergeant found out the hard way. He bonked his head in the underside of the cannon, and discovered Donald inside. He blew hard into one end of the barrel, sending Donald into the bucket of invisible paint. Donald makes use of his new-found invisibility by playing, stealing pies, and humiliating the Sergeant.

The Sergeants antics convince the General that he is crazy, especially after he stole several grenades from the arsenal and started blowing things up. At the end, the Sergeant is locked up in a cell, wearing a straitjacket. He pleads to Donald (who is on guard duty): Im not crazy! Go tell the General that I aint crazy! To this, Donald replies, Do you think Im crazy?