The Worst way to die? hmm theres a few,

1) Having your body tied to a cage of rats and then having something designed to create panic in the rats eventually the rats will take the only viable escape which will be to eat through your body to escape! (read 1984 by George Orwell they did something similar in this)

2) Being boiled to death, A torture method used in Feudal Japan to make people speak when held in captivity, if several members of a band of bandits were captured to make them reveal the identity or location of their leader/base. They would take one and place him in a large cauldron over a pile of wood (the water would be cold at first) then they would heat the water up and boil the man alive. It is said that they could keep a man screaming in agony for almost 7 hours. If the man did not die of the pain before the dawn (for this was almost certainly done at night to make the cries carry to his imprisoned comrades who knew the next night one of them would be taken) he might just be granted mercy and executed by a samurai who was attending. Read Sho-gun by James Clavell for more details (a work of fiction but the torture method was real.)