Jackpot
A jackpot may refer to a number of things, including such disparate things as “a tight spot, or difficult situation” and “an impressive often unexpected success or reward.” Both of these meanings are figurative ones, and the earliest sense of the word was a somewhat literal one, as it was used in reference to a pot and jacks. The pot in question was the accumulated bets made in a poker game, and the jack came from the provision that a pair of jacks was necessary to begin betting.