I hate contests for small children. I would say that all of the kids that color a picture win free dinner for a month. I wouldn't even call it a contest.
Picture this: A 4-year-old boy and his 3-year-old brother both color pictures for the "contest." The 3-year-old wins. So, for a month, the family comes to eat at this restaurant, and the 3-year-old gets to eat free. The 4-year-old didn't win and, therefore, doesn't eat free and is reminded for a whole MONTH that he didn't win the contest.
Picture this: A very sensitive, perfectionistic 5-year-old girl thinks that she is best "colorer" in the world. She colors a picture for the contest. A 4-year-old wins the contest. She gets really upset because she thought her picture would be the best. Every time she comes in your restaurant, she has bad feelings because of the contest she lost.
I would hate for any child to feel that way, and I personally would hate to be responsible for any child feeling that way.