09/29/2011 at 12:00 PM EDT
It's a jungle out there – and Anderson Cooper knows this better than anyone. The reason? He was greeted by a llama on Wednesday outside David Letterman's New York City studio.
"Strange who u meet on NY streets," he Tweeted
, adding a photo of himself standing next to the fluffy white creature.
The llama, who Cooper petted in the green room
before his interview with Letterman, was a pal of animal expert Jack Hanna, a guest the previous evening.
During their chat, Cooper and Letterman argued over whether or not the late-night host had been invited to appear on the CNN anchor's new daytime talk show.
"I think I would know if I'd been invited," Letterman quipped.
"I said, You know what? Dave's too busy but I'll come and see Dave on his show and sit in a room with a llama," Anderson joked.