On Staunton Island, one of your payphone missions is "Uzi Rider". In this mission, two gang members pull up in a perrenial. You are to get in, drive to Portland, and kill some filthy diablos by drive-by's. Do as they say, and do the first part of the mission, after you are done and are heading back to Staunton, park in the blue circle. The mission is now complete. They get out of the car and you are left with it. When they start to walk away, run over the one that walks to the left. If you kill him, he should have a lot of money.