Man in Black: You guessed wrong.
Vizzini: You only think I guessed wrong! That's what's so funny! I switched glasses when your back was turned! Ha ha! You fool! You fell victim to one of the classic blunders - the most famous of which is "never get involved in a land war in Asia" - but only slightly less well-known is this: "Never go in against a Sicilian when death is on the line"! Ha ha ha ha ha ha ha! Ha ha ha ha ha ha ha! Ha ha ha...

[Vizzini stops suddenly, his smile frozen on his face and falls to the ground dead]
Man in Black: [Removed blindfold from Buttercup's head] You all right?
Buttercup: And to think, all that time it was your cup that was poisoned.

Man in Black: They were both poisoned. I spent the last few years building up an immunity to iocane powder.
— The Princess Bride (1987)