Josh Groban's first taste of the movie industry tasted like cherries?

While filming Crazy, Stupid, Love, his big-screen debut, the crooner ditched his nice-guy persona to play Emma Stone's bad-boy boyfriend - a comedic role that came with a little romance.

"After one of our scenes, the directors said, 'This is feeling a little goofy. Let's try this with a kiss at the end,' " the freshly minted actor, 30, tells GQ magazine. "And I thought, 'Holy s---! I've never kissed on-camera before. What do I have to do? I didn't take that class in college.' "

Luckily for Groban, "Emma's just this total pro."

He recalls of his first on-screen smooch, "She pulls out her lip gloss and says, 'It's cherry. That cool with you?'"

Although the shot didn't make the cut - maybe the "blooper reel," he cracks - he likened the scene with Stone, 22, to another pivotal film moment.

"That kiss shall forever be my deer in Stand by Me," he says. "It's my moment alone. No one but me will ever be able to treasure it."