Question: There is a kingdom and in the kingdom when you drink a poison the only way to cure yourself is to drink a stronger poison to neutralize it. The King wants to make the strongest poison possible in order to make sure he can neutralize any other poison he may be given. To do this he enlists the two best chemists of the land: Tom and Bob.
The king is going to have them both create a poison as strong as they can then have them drink the other person's poison then their own. Whoever dies created the weaker poison. Tom knows that Bob is much better at making poisons and he is sure to make a stronger poison. Knowing this, Tom makes a plan that ensures he lives and Bob dies.
The day of the contest arrives and Bob realizes that Tom must have known he had no chance against his prowess as a poison maker. So Bob thinks quickly and creates a new plan that ensures that once again he will live and Tom will die.
In the end Bob lives, Tom dies, and the King doesn't get what he wants.
Answer: After Tom realized he was going to lose he finds that the only way to live is to replace his poison with something that isn't poison at all and drink a poison of his own before the contest. In this way he drinks his own weaker poison then neutralizes it with Bob's stronger poison. Last he drinks the non-poison he submitted to the contest.
Once Bob realizes that this is the only way Tom can save himself he figures out that he can save himself by either drinking a weaker poison before the contest so his neutralizes it in the contest or submit a non-poison to the contest as well. If he drinks a weaker poison before the contest both Tom and Bob will live and the King will realize that they are disobeying his orders which probably won't turn out well. But by submitting a non-poison to the contest as well Tom will end up drinking the weaker poison before the contest and the two non-poisons in the contest and he will still die, and the King will be none the wiser (although he will not get what he wants being that both of the poisons actually aren't poisons at all).