Not to be confused with the M79 Grenade Launcher.
The Grenade Launcher is a weapon introduced in Share The Pain, and featured exclusively in the original AWP and is basically a recolored Rocket Launcher that launches grenades instead of rockets. It does not require any reload, and can continuously fire grenades, which will explode shortly after landing, or instantly if they make contact with a living being. In Postal 2 Complete, it is replaced with the M79 Grenade Launcher.
In Enhanced mode, this weapon shoots exploding cats.