Go to the airport on the first island, and on the runway will be long yellow obstacles on the grass with writing on it reading 'CAUTION YOUR BLAST'.

Use a motorbike and go as fast as you can over it, and you can do backflips etc. You can also use cars, but for an awesome stunt, use a car, and go over the edge of the obstacle, with only half your car over it, and you will do about 5 spins in the air.

NOTE: As soon as you go on the runway, your wanted level goes up to 4 star.