Buying a water gun at Target is all well and good, but you'll have the same equipment as everybody else. If you want a leg up, you need to build it yourself. And you might as well go crazy.
Sure, you'll need a whole bunch of stuff such as PVC piping, ABS, springs, hose clamps and valves to build this awesome thing. But it's able to have a constant stream as you hold the trigger down, which is more than you can say for many of the store-bought guns your foes will be saddled with. And that's what counts. [Super Soaker Central via Hack-a-Day via Make]