Turn your car around, follow the street to the end, and turn right. Follow this next street to the end, and turn right. After you turn right, there will be some buildings to your right. At the end of those buildings is a fenced in area. Follow the fence, stop at the last section, and look left. You will see the switch next to the building. Turn your car around and park. Get out of your car and walk over to the switch. Press Triangle to open a secret area. Get back into your car and follow the fence. About half way down you will see two rows of palm trees. That is the entrance. Drive in to reveal the secret game, around the back of the building. This secret game can also be unlocked by winning the Undercover mission.