The Teenage Mutant Ninja Turtles eat Domino's Pizza. Michelle Pfeiffer drinks Coke in the upcoming "Frankie and Johnny." With more and more companies paying to have their products pop up in films, public-interest activists are petitioning the Federal Trade Commission to regulate the practice. "It's the most deceptive form of advertising because the audiences aren't told it's an ad," says Michael Jacobson, cofounder of the nonprofit Center for the Study of Commercialism. His proposal: require films to name paying advertisers in the opening credits.