There's nothing Adam Sandler loves more than making his daughters, Sadie and Sunny, laugh - but it's proving to be more of a challenge these days. "They used to laugh easier," Sandler, 59, admitted to David Letterman during a special episode of his series My Next Guest Needs No Introduction. "Now they're older and they judge you a little bit. I do hear, 'Oh, don't say this.'" Still, getting his two teens to crack a smile remains the "greatest thing" Sandler can hope for. "You're happiest when they're happy," he said.