Abstract: An assembly for creating water balloons that directs water from a water source into a manifold. Filler straws extend from the manifold. Latex balloons are readied for filling by placing a neck plug into the necks of the balloons. Each neck plug has an elastomeric body that is sized to plug the neck of the balloon. A blind bore is formed into each of the neck plugs. The fill straws are advanced into the blind bores of the neck plugs. The filler straws are advanced deeper into the neck plugs, therein piercing the material of the neck plugs and eventually passing through the neck plugs. Due to the elastomeric material of the neck plugs, a watertight seal is formed around the filler straws. Water is advanced through the filler straws to fill the balloons.