A short, extremely fatass girl (always with dark brown/black hair) who looks startlingly like a monkey. The Thunder Monkey is usually seen eating whatever she can, and as much of it as possible. She even enjoys chugging mayo and anything else in a packet. Usually needs to wax her eyebrows.
Person #1: DAMN! Look at that Thunder Monkey!
*Thunder Monkey is in the distance in a cafe, chugging ketchup packets*
Person #2: Look away before you're blinded! LOOK AWAY!!