Mariska Hargitay, who turns forty-eight today, has been playing detective Olivia Benson on Law and Order: SVU for twelve and half seasons, two-hundred and eight-five episodes, and countless USA marathons. Between consoling abuse victims and interrogating perps, there are a lot of emotion she has to express. There’s horrified, confused and horrified, scared and horrified, not to mention disbelieving and horrified. If you find yourself tuning in half-way though an episode, you might not understand what one of her particular open mouth gapes means. Luckily we’ve made up a handy classification guide for you.