The Kumbh Mela, held every three years in India, is the world's largest religious gathering, with 100 million people in attendance. To reach out to this group, OgilvyAction and Lifebuoy, a germ-eliminating soap, teamed up with restaurants and cafes at the site of the gathering to spread its message -- that washing your hands regularly can kill most germs and keep you healthy. It stamped a message on rotis -- Indian flatbread mostly eaten with your hands -- that were being served at the restaurants. It read: "Did you wash your hands with Lifebuoy?" Over 2.5 million rotis were heat stamped with the message, and the brand also put up billboards and banners over the site with the same message.