Who hasn't seen a lost child, tear-stained cheeks, crying in an amusement park or at an airport? Parents might feel less anxious with a product called Safetytat (www.safetytat.com), a temporary, stick-on tattoo on which you can write a phone number. They come six to a pack, with a marker (about $10).  (Ken Kwok/Los Angeles Times/MCT) Photo: Ken Kwok / Los Angeles Times