To make a lot of money fast, go to the freak show and make a bet (max bet is $100) on the wrestling match. You can pick either wrestler to win, it doesn't matter. Stand next to the ring when the match starts.

Eventually the wrestlers will get close enough to you that you can land a few punches to the one you bet against. Be careful not to punch your own wrestler! This will knock his health way down and he'll be finished off easily.

You'll get a "Violence Against Children" in your violence meter, but it doesn't matter because there aren't any police in the freak show tent.