That's a knife...

[Aristotle]

Crocodile Dundee might even appreciate this one.

WASP Injector Knife

The trouble is, if your shark, elephant or enemy combatant is close enough for you to stab them, they're well within range to lay some serious hurt on you if your knife aim isn't true - and there's plenty of angry animals out there capable of disposing of you even with a blade hanging out of them. That's why WASP have created the Injector Knife, which forces a massive charge of freezing compressed air into the stab wound. WASP claims the shock and tissue freezing can stop the largest of land predators in its tracks, and it's even more effective on underwater predators.

The WASP knife is fairly simple in principle; the removable handle contains a bulb of compressed gas, and there's a thumb button which releases that gas almost instantly through a thin tube that exits near the point of the blade. The gas is expelled at around 850psi of pressure, and expands to around the size of a basketball inside whatever the knife has been poked into.

...

The initial gas release is extremely cold, and can snap-freeze all tissue and organs in the area surrounding the blast, which has a devastating and instant effect on the hapless victim. The effect is compounded if used on an underwater predator - not only is there the instant shock and freezing effect, but the large injection of air causes the recipient to float upwards, and as it rises and the atmospheric pressure decreases, the ball of air continues to expand with catastrophic consequences.

The WASP Injector Knife is also virtually silent when discharged inside an enemy's flesh - not that the enemy can be expected to remain silent through such internal trauma - but it effectively maintains the knife's potential as a stealth killing option while massively multiplying its lethality.

[Talsek]

That sounds completely badass. Besides, it combines knives and compressed air - two independently awesome inventions. They should make miniature versions of that knife, which you can fire through a tube using more compressed air. Little frozen death snacks, woohoo! Slightly less practical, of course, but seriously fun.

[Darion]

This invention sounds awesome and I would very much like to stick someone with it.

[Savaric]

Originally posted by Darion
This invention sounds awesome and I would very much like to stick someone with it.

Hahaha, hilarity is all in the sentence structure.

[Savaric]

They'll make it illegal as soon as someone starts using it as a stealth murder weapon. Or peta will put an end to it.

I would still rather have a .44 magnum for large land predators. Plus, you can use the gun to change the channels on your tv (I saw it on the simpsons).

[Theairoh]

This doesn't look very practical, to be honest. Very suave, but impractical.

[utugra]

Originally posted by Darion
This invention sounds awesome and I would very much like to stick someone with it.

I misread invention as invasion and am wondering how long it is till we are invaded by some Demon Scorpiens capable of using this ability.

[Tartun]

I would still rather have a .44 magnum for large land predators. Plus, you can use the gun to change the channels on your tv (I saw it on the simpsons).

Actually, Elvis shot T.V.s as a hobby. That wasn't just a joke. He had so much money he just bought televisions and if he didn't like what was on, he would shoot the tube. On another note, that knife is an awesome invention, very lethal, and it sounds like it wouldn't be that hard t make yourself if they outlaw it in your state.

[Rosuav]

The gas is expelled at around 850psi of pressure, and expands to around the size of a basketball inside whatever the knife has been poked into.

Err, it's a gas. Someone's forgotten the laws of physics. Or do all living creatures have the same internal pressure?

[Jyn]

I really don't think that that knife will slow an elephant down enough to stop it from crushing you if that is its intent. It would probably make it go rapidly mad and the goring/crushing/bashing will go that much worse for you.