The Pocket Sized Grenade is an explosive paranormal deterrent used by the Sanctum of Slime Ghostbusters of Dimension 50-S.
During the initial encounter with Wat, the Sanctum of Slime Ghostbusters were blasted and hoisted up towards the ceiling. Gabriel Sitter reached for the Pocket-Sized Grenade in his flight suit's front pocket and threw it at Wat. The explosion dazed Wat and partially revealed its true form. The Ghostbusters used the opening to trap it or so they thought. Samuel Hazer admitted he never thought the stupid grenade would work.