The paradox is this: When playing “Let’s Make A Deal“, do the player’s chances of getting the car (behind door number 1, 2, or 3) increase by switching doors once a guess has been made (so technically it’s down to two doors at that point)? Surprisingly, the answer is Yes and the Monty Hall Problem explains why.
OMG! The amount of time and math that went into that is hilariously amazing.
Wikipedia’s explanation is excessively thorough, but that’s the fun of Wikipedia. The autistic boy in The Curious Incident of the Dog in the Night-time did a much more efficient job of explaining this dilemma.