NEW YORK A new Ad Council campaign created by Merkley + Partners in New York warns teenage girls to “Think before you post.” A spot called “Everyone Knows Your Name” illustrates just how dangerous it can be to post personal information online. The spot opens on a shot of three teens walking out of their school, when a handsome boy says hello to “Sarah,” who smiles at the attention. As the spot progresses and Sarah goes about her day, the greetings become increasingly disturbing, from boys her age noticing her to older men in her path. First the school coach says hello, then a movie ticket agent asks her, “What color underwear today?” and finally a waiter asks, “When are you going to post something new?” before the spot urges young girls to “Think before you post.” The campaign was created in conjunction with the U.S. Department of Justice and the National Center for Missing and Exploited Children. The ads direct viewers to www.cybertipline.com, where visitors can report an incident or get advice on preventing online sexual exploitation.