This mission is given by Giuseppe Palminteri.
"Joe, thank God you are here. Three of my best customers pulled a big job that went bad. I just found out the cops are looking for them and I worry they will catch them soon. It is very risky for me to be on the street right now. Can you warn them? Joe, I've known these customers for years. They are like family. Do this as a favor for me, please."
This mission is pretty simple, as there's no gunplay involved, just a whole lot of driving. Depending on traffic and how well you drive, the mission might get a little close on time. It's best to use a fairly quick car and not to obey the speed limit along the way.
Start the mission and get in your car. The GPS may direct you to head to the marker to the west when you start off, but you'll want to go to the northern most one first.
Drive to The Dragstrip bar, where the guy will be standing outside with a large green arrow above his head. Just run up to him and press the action button to warn him, then jump back in your car.
Playboy magazine #16 is located in the Dragstrip bar, where you stop to warn the first guy; however, if you think you might run close on time, it's probably best to just grab it later.