CNN anchor Anderson Cooper joked on Late Night that host David Letterman sets off his gay-dar.

Cooper, who came out gay last year after ducking rumors for years, appeared on CBS' late night talk show on Friday.

Letterman wanted to know whether Cooper had gay-dar.

“Gay-dar is there … do you have the … you hear a lot about gay-dar,” Letterman said.

“I know, I know, yeah, it's a good question,” Cooper answered.

“I'm pinging off the hook about you Dave,” Copper joked. “Look, I can sometimes tell when somebody else is gay. But I'm eternally surprised. I mean, there's people I always thought were gay and are not, then there's people I never knew were gay in a million years and turned out to be.”

“But it doesn't exist any more than human intuition exists ...”

“I don't think there's some sort of … there's not a secret code that we've all learned from a young age. There's not a secret like handshake,” Cooper added. (The video is embedded on this page. Visit our video library for more videos.)