How Do You Play Dirty Santa?

We are supposed to play Dirty Santa again this year at our company Christmas party. I think some people call it Secret Santa. I'm not a real big fan of this game. I don't think anyone knows the right way to play it.

I've had to endure it at work parties and family gatherings. What are the rules? Steal once? Twice? Gift is "dead" after have many steals? Do you bring good gifts or gag gifts? Do you know how to play? I combed though the depths of the internet and found dozens of rules and none of them are the same.

Can you give us some clarity?