An extremely
poisonous substance, featured in the "
battle of wits" scene in
The Princess Bride.
Vizzini and the
Man in Black sit at opposite ends of a
table, and the
Man in Black claims that he has put iocaine powder in one of the two
goblets of wine on the table, and gives him the
option of switching them or not before they both
drink from their goblets.
Vizzini then uses an extremely
recursive line of reasoning to decide which
cup is poisoned. Watch the
movie if you want to see the
result.
Iocaine Powder is also the name of an algorithm that won an AI Rock-Paper-Scissors contest, using similar reasoning.