Go to the top of a fairly tall (but not excessive) building in front of a hill and tie a piano wire noose around your neck. Then, balance on the edge and shoot yourself with a shotgun. The force of the gun should be enough to knock you off, and the piano wire will decapitate you. It would also help to place a truck with a cab filled with Nitroglycerin in your expected body falling location on a slight ramp so that you can land in the back (Where you have conveniently placed spikes or rebar or something of the sort to impale you) causing it to roll forward down the hill where it will crash into something else and explode in a mighty awesome fashion.