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Actor-Singer Justin Timberlake stopped by the Late Show With David Letterman to promote his latest film In Time last night, and Letterman asked the actor-singer if he’d ever be in a musical.

“That’s been discussed,” said Timberlake, however he’s “not really” comfortable with the roles available. “I would love to do a musical one day. I think there might be a way to redefine what that is for this era,” said Timberlake. “My problem with musicals today, and I think in my generation, is that we’re sitting her heaving a conversation and all of the sudden we’re singing. Time stops.”

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At that point Timberlake pointed at Letterman’s coffee mug and sang, “What is he drinking in that coffee mug?”

Pitched in Letterman, “La-la-la-hey-hey!”

Watch Justin’s appearance on Letterman…