No, the Wasp Injector Knife is not a weapon for dispatching Vanderbilts and Roosevelts (although doubtless it could be pressed into this service). It is a surgical stainless steel knife with a gas canister in the handle. When you stab a victim, the knife "injects a freezing cold ball of compressed gas, approximately the size of a basketball, at 800psi nearly instantly."

It is primarily for use by divers, where the sudden injection of gas will cause Jaws (or any other leviathan) to speed toward the surface before they burst, effectively removing them from the fight and also safely carrying their shark-baiting blood along with them. There are also hunting versions, and the site lists "tactical uses" amongst the features. However, this is only meant for self defense or justifiable revenge: The blurb also tells us that "WASP Injection Systems, Inc. does not condone the killing of innocent creatures."

Watermelons, however, are a different story, as shown in the manufacturer's video below.

We imagine more harmless uses – primarily pranks. Slip this into your dinner partner's place setting next time you are at the steakhouse and watch as hilarity ensues, transforming the dining room into a scene from the Texas Chainsaw Massacre. From $380.

Product page [Wasp Knife via Uncrate]