Empty soda bottle (Fallout 3)

The  is a clear glass bottle in Fallout 3 and Fallout: New Vegas.

Fallout 3
The empty soda bottle only serves as a common form of Rock-It Launcher ammunition.

Fallout: New Vegas
You can squeeze the water out of three Prickly pear fruits into an empty soda bottle to form a bottle of Purified Water which essentially is Cactus water.

Locations
There are four in Goodsprings gas station where Ringo hides. There are also six in front of Gibson Scrap Yard to the right, by the REPCONN "O" Chair in a box near Novac. There are four in REPCONN Headquarters first floor, if you walk into the tour part, its in the gift shop to the left, along with four Lunchboxs.