After reading this post on con men, I came up with my own way to earn $20 while in a bar.
First you search for the densest person in the room. Blondes, drunks, and blonde drunks are usually a good target for beginners. And then you approach your target, do some small talk, and let it slip somewhere in the conversation that you are a fortune teller. The natural reaction of most people is one of curosity and this leads to questions of you to prove your fortune telling abilities.
Then you, the swindler, backtrack a bit and say "well, I'm only right about 50% of the time. But I'm willing to bet $20 on it."
Then you take a twenty from him and then tell him "Go into the bathroom right now you'll see a fire-breathing unicorn."
The target goes to bathroom and you move around the corner and wait. When he comes back and finds you, you instantly say "I knew you'd come and ask for your money back!" And then you pocket his twenty dollar bill.
I thought you might like this. You can get up to $500 ($250 increments) of the $1 president coins from the US Mint shipped free. The shipping disappears when you go to the final checkout screen. This is cool for a couple of reasons.
1) coins are cool and dollar bills are such a pain in the balls. So, circulate these things.
2) If you want to be a true cheapskates, you can buy these with a credit card and get whatever rewards, x%, skymiles, etc. I suppose you'd have to carry 10lbs of coins to the bank if you just wanted to deposit them, but hey. You could look at this as an immediate 2% (or whatever cc rewards you have) on a $500 investment.
3) who doesn't like Andrew Jackson?
All solid points. I'd also like to add a part 4 to this if you still aren't sold on coins. This is from the old Comedy Central show Upright Citizens Brigade: