In this illusion, you can see two things. First of all, there is a man on the girl's back. Is he from the Lilliput? And her reaction is nothing unusual as if he had been that way all the time. Secondly, the leg of this girl is abnormally long and with awkward shape. Well, answering the first thing, the guy is sitting on the bench that you can see on the left most of the picture. The pattern on the girl's top matches with the color of the man's pants and the positioning is perfect so that they appear to be overlapping. Secondly, that is not her leg and the arm of a person sitting out of the focus of lens that clicked this picture. Again, the position is causing an illusion.