Extra-terrestrial beings have always been existing in our imagination, a green or grey creature with a very thin body, bulging eyes in a large head, riding in a highly-advanced flying saucer, abducting humans. They are perceived to be friends or foes. Back then, people believed that they live in planet Mars, yet if they ever did, information should have been spread around the globe. Centuries have passed now but their existence lives on in our brain as be continue to believe that there are other living creatures in the vast universe. Setting aside the E.Ts, in a funny way, the real aliens are those who step into a foreign land and are usually called tourists.