"Who Is That?" joke

One day, Bubba was bragging to his boss, "You know, I know everyone there is to know. Just name someone, anyone, and I know them."
Tired of his boasting, his boss decides to call his bluff. "Ok, Bubba, how about Tom Cruise?"
"Oh sure, Tom and I are old friends, and I can prove it," Bubba says. So, Bubba and his boss fly out to Hollywood, knock on Tom Cruise's door and, sure enough, Tom shouts, "Bubba, it's great to see you! You and your friend come on in and join me for lunch."
Although impressed, Bubba's boss is still skeptical. After they leave Tom's house, he tells Bubba that he thinks Bubba's knowing Cruise was just lucky.
"No, you're wrong," Bubba says. "just name anyone else.
"President Bush," his boss quickly retorts.
"Yes," Bubba says, "I know him. Let's fly out to Washington," and off they go.
At the White House, President Bush spots Bubba on the tour and motions him and his boss over, saying, "Bubba, what a surprise! I was just on my way to a meeting, but you and your friend come on in. Let's have a cup of coffee first and catch up."
Well, the boss is very shaken by now, but still not entirely convinced. After they leave the White House grounds, he expresses his doubts to Bubba, who again implores him to name anyone else.
"The Pope," his boss says.
"Sure," Bubba replies. "My folks are from Poland, and I've known the Pope for a long time." So, off they fly to Rome.
Bubba and his boss are assembled with the masses in Vatican Square when Bubba says, "This is never going to work. I can't catch the Pope's eye among all these people. Tell you what, I know all the guards so let me just go upstairs and I'll come out on the balcony with the Pope."
With that, Bubba disappears into the crowd headed toward the Vatican. Sure enough, half and hour later, he and the Pope come out on the balcony together. But, by the time Bubba returns, he finds that his boss has had a heart attack and is surrounded by paramedics.
Managing to reach his boss' side, Bubba asks him, "What happened?"
His boss looks up and says, "I was doing fine until you and the Pope came out on the balcony and the man next to me said, "Who is that on the balcony with Bubba?"