A dreidel is a pointy, four-sided top which can be made to spin on its pointy base. There are Hebrew letters on each one of its sides, which stand for deep cabalistic notions but can also serve in small-time gambling.

Assuming you're not a kabalist, you need to know this:

  Nun stands for nes, miracle. If you roll a Nun you neither pay nor     gain anything.

  Gimel stands for gadol, great. If you roll a Gimel you win                 everything.

  Hay stands for haya, was. If you roll a Hay you win half.

  Shin stands for sham, there. If you roll a shin you lose everything.