The pool cue is a tool and a weapon in Grand Theft Auto: San Andreas and Grand Theft Auto IV. It seems to have the longest reach out of all the melee weapons, but it's main use is just what the name says.
GTA San Andreas
Challenge someone to a game of pool in a bar somewhere, and after beating them on the table, the player can keep the cue to smack people around with. Even the game is lost, the player is still a winner! Though it is an effective meleé weapon, the player cannot sprint, because of the pool cue's length. Any meleé weapon the player has will be replaced by the Pool Cue.
- Blueberry, Red County - In front of a small restaurant. From the entrance of the Blueberry Well Stacked Pizza, head east and through the four-way intersection. Continue until your reach the next intersection which should be a three-way. At the northeast part of this intersection you should see a small restaurant. The Pool Cue is just north of the entrance.
- Doherty, San Fierro - Underneath a fallen part of the building on the west side of the Construction Site north of the Doherty Garage. From the entrance of the Doherty Garage, go north and turn west when you reach the corner of the Safehouse. Continue west and up the hill into the Construction Site. Continue west and you should encounter a still-standing portion of a building with the floor drooping down. Underneath this fallen floor is the Pool Cue (and a Flamethrower).
- Rockshore East, Las Venturas - In the middle of the industrial complex (by the dumpster) at Rockshore East. From the Rockshore West Safehouse, head north through the intersection and turn east at the road curve. Continue east and turn north at the next road curve. Continue north and turn east at the next road curve. Continue forward, cross the railroad tracks, and enter the industrial complex. Just off to your left is some sheltered parking. Go to the east end of the sheltered parking area. When you get there you should see a beige building off to your left. There is a dumpster at the southwest corner of this building. The Pool Cue is next to this dumpster.
In GTA IV, the pool cue is used to play pool but cannot be used outside it even though it's a functional weapon. The pool cue can be used as a weapon in the downloadable episodic pack The Lost and Damned for Grand Theft Auto IV.