A Rebillard is a person who typically shows up about 5-6 hours later than when he says he will arrive. A Rebillard will lie about most things, and when caught in a lie, will defend it even when he is blatantly wrong.
Rebillards tend to have wide faces, and talk a lot like Cartman, from South Park. They will cheat at any game they participate in and than rub it in your face ruthlessly.