I haven't played this game in a long time, so cope with me. In the planet where they have the robot tours, stand on the departure pad where the robot tourists get off the bus. As soon as one arrives, use Ratchet's boomerang wrench (R1+Square) and keep terminating the robots the come off--don't let even one get away and KEEP TERMINATING THEM. After a long while of killing tourists, there will be a message from Megacorp. I think there are 4 messages that come up, but I don't remember, so keep killing tourists.