Go to the Pizza Job located on the Second Island/City Island/Middle Island, Then you wait until 12:00 PM at Midnight, and start the job, (You may notice different music) Because this time you have to Deliver a pizza to aliens, (P.S. You MUST wait until 12:00 PM - 12:59 PM or you wont get the secret job)

Follow the UFO (Don't try to catch it or catch up to it) Cause the UFO will lead you up to the top of the Snow Mountain on the Third Island/ Top Island, once he goes to the top, he will stop at the hockey sage, Bring the Pizza over to it at start floating up, once done so, You will complete the job and the UFO should fly away with a Pop-Up at the top of the screen saying you unlocked the Alien Outfit, AND BOOM, You just unlocked yourself the Alien Outfit/ Jetpack!