Hey, wait, I'd actually like to see lipstick on a pitbull! After doing some web research, I found that another option would be to do "McCanine".
Or, what would be really cool, since the costume contest is right before the election, is a sort of Push-me-pull-you (from Dr. Doolittle) utilizing Bark Obama AND McCanine shirts, going opposite directions! (But which end for the head, and which end for the tail?

Hmmm...)