Vaughn keeps mum

Vince Vaughn

Though Vince Vaughn and Jennifer Aniston have been mum about their romantic relationship, they aren't fooling David Letterman.

With Vaughn as a guest on The Late Show, Letterman took the approach of presuming the relationship, which has not been officially confirmed.

"Hey, nice going on that Jennifer Aniston thing," he told Vaughn.

Letterman also told the actor he thought they made a nice couple.

But when he asked the actor outright whether he and Aniston were a couple, Vaughn responded, "I'm not saying we are or aren't a couple. I think she's great, but I just don't discuss whether we are."