A great and easy to do trick. You can cut out a small hole and by bending the paper just right you can fit a much larger coin through it. This "large coin, small hole" bar trick is a great way to win money, beer or even just to impress the best.
Fun Party Tricks provides tons of great howto videos for cool party tricks. These videos are free and easy magic tricks that allow you to show off your skills at a party or bar.