I have to believe that some company, somewhere has developed a squirt gun that could be mounted on a garden hose—but I doubt it looked as cool as this concept version.
The "Garden Gun 5.1" was designed as part of a project called The Design Reaktor Berlin. Apparently, the driving force behind the project is to facilitate collaborations between up and coming designers and small to medium-sized companies. It's not going to change the world, but I would feel like more of a man watering flowers with this than I would with a traditional hose gun attachment. [Design Reaktor via Trendhunter]