Waluigi is the twin brother of the Fartudinous Lump of Poo. He is the exact opposite of him. He's skinny, doesn't lounge like him, and can dance better.
Wario: STOP COMPLIMENTING MY BROTHER.
Wario: Sheesh. I need to eat healthier.
Waluigi: Yeah, you're a fartudinous lump of poo.
Wario: SHUT UP.