When I was in college the homeless had an entrepreneurial idea of hangout out around the bars Thursday through Saturday night. I found this annoying but soon discovered a system.
Rule #1: don't make eye contact.
Rule #2: if you do make eye contact, be sure to ask them for money before they ask you.
It makes it easier to do rule #2 when you're drunk. Regardless, this immediately stuns the homeless. They don't know what to say, but the key is persistence. I had to ask him 10 times nonstop for a $1. Finally since I was interrupting his business of asking others for money he finally relented.
He takes out a wad of $1 bills and peels me off one. "Here! Now go away!" he firmly tells me. Feeling like I just won the lottery I got greedy and pestered him for another $1. This backfired.
He soon turned the tables on me annoyed me to the point to where I gave it back. He was more street wise than me at the time and I learned my lesson.
Always ask for a dollar first and leave as soon as you get it! Now you know and knowing is half the battle. Also don't forget to report this dollar on your taxes.