How do You Play Dirty Santa?

There are a few variations of this game but the general idea is you have a group of people bring gifts to an event and then you write numbers from 1-how many people are at the party on little pieces of paper and have people randomly pick a number. The person with #1 will go first and so on as people get to their turn they can either keep the gift they choose or steal a gift from someone who went before them so the last person actually has the best position in the game.