Radio star Stern appeared on Letterman's CBS program Wednesday night.
After the two complimented each other on growing more handsome as they age, Letterman pulled out a photo of Stern as a guest on his former NBC series "Late Night" back in 1984.
Stern is sporting a mustache and large glasses in the snapshot.
"Yeah, you should burn that," Stern joked.
"There I am, wow! And the mustache worked for me, didn't it?" Stern later said. "Dave, I swear to you, back then, the fact that you asked me to be on a national television show was mind-blowing to me."
"It looks like a guy who was on to talk about a career of writing bad checks," Letterman quipped.