After your previous adventure, you finally reach some treasure! You're in back luck, though, as you encounter two chests, one of which contains gold, the other a lethal gas. What's more: you can say one statement, if it is true, one of the chests opens, if it is false, the other one opens. If you statement is not true nor false, or both true and false, you instantly drop dead.
What statement will make you survive and bring you many riches?
The main trick is to take advantage of the contents of the chests; good statements could be "if this statement is true, the chest containing gold will open", or "if this statement is false, the chest containing the lethal gas will open".