At the beginning of the game when you are on the GFS Olympus, head to where your gunship is sitting. Adjacent to the ship will be two beacons that, when shot, will head upwards in the air. With careful firing, you can juggle the two beacons in the air, shooting them higher and higher. If you manage to hit one twenty times in a row without missing or the beacon hitting the ground, you will be rewarded with a friend voucher.