Guaranteed $20

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.