"Do you think I was invited? I wasn't invited. Terrible!" Stern said, standing in front of his desk. Before Letterman, 68, could defend himself, Stern asked the host to follow him to the middle of the stage.
Nervously, Letterman walked into the spotlight with 61-year-old radio host, who began to grab the host's jacket lapels.
"What are you gonna do?" Letterman asked, trying to back away.
"Come here and hug me," Stern said, pulling him in close. They held their embrace for a moment before Stern went in for the lip lock.