Empty Whiskey Bottles are a throwable item found in almost all lootable locations. Selecting the bottle (or any throwable item) and "firing" will throw it just as one would throw a Grenade, with distance determined by angle of throw and how long the fire key is held down.
The sound of a thrown bottle breaking will attract the attention of nearby zombies, who will investigate the noise. Bottles can thus be used when surrounded by Zombies to create an escape route. They can also be used to break hospital windows or distract other Survivors.