I easily can imagine Benedict XVI sitting in his Vatican apartment...

...humming, "Where to now, St. Peter?"

On this, the day of the resignation of Pope...

...Benedict XVI, I offer this anecdote about Frank Sinatra's meeting with Pope Pius XII during World War II, from Don Dwiggins' Frankie: The Life and Loves of Frank Sinatra (Paperback Library, 1961):

     Despite Stars and Stripes' comment that Sinatra had "wised up His Holiness on the crooning racket," [Phil] Silvers remembered that Frank's audience with the Pope was constrained.  The Catholic leader had heard of Sinatra, but knew little about him.
     "You are a tenor?" he asked.
     "No, Your Holiness," Sinatra answered. "I'm a baritone."
     "A baritone," said the Pope. "What operas do you sing?"
     Sinatra hesitated a moment. "I don't sing operas, Your Holiness.  I've never studied singing."
     The Pope smiled and changed the subject.  After the interview, when Silvers suppressed a grin, Sinatra threw away the line of the year: "Well, what the hell was I supposed to tell him? That I sang "Old Black Magic?"  (68)