Uncle Mortimer, the crazy doctor with a PhD in "Funology", and the creator of the Thrillville amusement parks, is quite the character. Now, with this simple article, you can easily dress like good ole' Uncle Mortimer.
Get a paisley button-up shirt. It can literally be of any color, as long as they clash (though green is preferred).
Wear a pair of tan or brown cargo pants.
Wear a yellow necktie, and let it hang loosely.
Wear a white lab coat. Don't button/zip it up.
Wear a pair of random shoes. They can range from sandals to boots.
Wear a pair of goggles over your head.
You can wear a crazy white wig, or dye your hair white with a non-permanent dye.
Wear a pair of plastic gloves, just to add some character to your cosplay.