The second-greatest living American born on May 8, Don Rickles, used to occasionally guest host “The Tonight Show” for Johnny Carson, before Johnny had permanent guest hosts like Joan Rivers and Jay whatshisname.

One night, when Don was hosting, Bob Hope made a surprise walk-on — which happened from time to time, when he was taping one of his prime-time specials in one of the other studios at NBC in Burbank. But this time, Bob brought a couple of friends with him:

Hat tip to Mark Evanier.

Bandleader Paul Shaffer, in his autobiography and on some of his appearances promoting it, told the story of Brittney Spears making a “surprise” (to the viewers, not Dave) walk-on for a comedy bit on “Late Show with David Letterman.” Shaffer told her in advance that he planned to play her on with “Thanks For The Memories” as a tongue-in-cheek reference to all of those walk-ons Bob Hope used to do on “The Tonight Show.”

Brittney’s response: “Who’s Bob Hope?”

Gee, I feel old.