Monday is Stay Out of the Sun Day. Of course, this is George Hamilton’s least favorite holiday. Or is it? “I don’t think his tan is natural,” says Kat Noel, an L.A. sun-worshiper, hula dancer and Pilates instructor. She watched with interest as Hamilton tangoed to high marks on ABC’s “Dancing with the Stars” this year (he also did the cha-cha and rumba) and drew a conclusion: He needs more sun. “If someone is going to be that tan, it should not look like it came from a bottle.” Hamilton, at right, didn’t return our calls so we don’t know the source of his hue. He’s usually not shy about his claim to fame: A while back he did ads for Nabisco Ritz Chips, endorsing the crispy snack by saying, “I know toasty.” Stay inside this holiday with two of Hamilton’s finest movies, both from 1960: “All the Fine Young Cannibals” and “Where the Boys Are.” Answer: the beach, obviously.