"McCARTNEY GETS AN EARLY BIRTHDAY TREAT IN LAS VEGAS" is the complete caption on this photo as it was submitted to us years ago by our photo partners. Lively and intriguing words, yes. Informative, no.
As a wild guess, the "early birthday treat" may have been a preview of the Beatles-related Cirque du Soleil show LOVE at the Mirage resort in Las Vegas. The first official performance of the show was on June 30, 2006, but according to Wikipedia, "Preview performances ran from June 2 to June 29. During these shows, including June 16 and June 17 which were attended by McCartney, changes were made nightly based on audience reaction, cutting or adding sections to add polish."
Paul McCartney was born on June 18, 1942, so one of those preview shows would fit quite nicely with an "early birthday treat" theme. As a double bonus, McCartney would have turned 64 in 2006, right in line with the famous Beatles tune "When I'm Sixty-Four." So we are now firmly betting on this explanation as being correct. Hey, this wasn't such a bad caption after all!