GIR is the best-known example of a malfunctioning SIR Unit. However, it is in question as to whether he can truly be considered a typical SIR Unit; since the Almighty Tallest hate Zim, and didn't want to give him a fully functional SIR Unit, they created GIR out of spare parts. In keeping with his composite structure, GIR rarely acts like a regular SIR Unit, and consistently displays erratic, hyperactive behavior and a complete lack of obedience. The only time GIR ever acts normally is when he is in "Duty Mode," a phenomenon during which one of the many loose wires in his head presumably connects, and he becomes fully functional.