I turned down a night out with my girlfriends to hang out with 7th graders. No, I am not Mary Kay Letourneau. My son is having friends overnight to celebrate his 13th birthday. I would sacrifice a dozen margaritas to make my children happy. They are my world. Besides, you know what happens when you leave kids home alone. They make a mess of the house, steal toothbrushes and play tricks on burglars. On the plus side, I get to watch Adam Levine on Saturday Night Live. I am not allowed to call tonight’s get together a party. There are no decorations and singing “Happy Birthday” was forbidden. They are…