Squirt Your Enemies Into Submission
The new 32 Foot Water Blaster does pretty much what its apellation suggests: it blasts 32 feet of water, thus ending fifty years of close-combat aqua-based battle. It's just about guaranteed that whoever wields this weapon of mass drenching is going to be the victor in any water fight he finds himself in, short of facing off against a squad of fire hydrant armed firemen.
The gun has two rotating nozzles that fire a wide-ranging blast of water as it's pumped. If Rambo was deserted by the US government in a water park instead of Vietnam, this is probably what he would use.