I was an intern on a concert shoot a year and a half ago holed up under the stage recording the camera feeds for MTV. Dark, loud, hot, boring.
But I was right next to the VIP entrance so I just hung out there all day (1.5 hour tapes) and met Jack White, Cee-Lo, DJ Danger Mouse, Anthony Kiedis, and came within arms reach (literally) of Pete Townshend and Roger Daltrey.
Other then that I had a teacher who saw Judge Judy at Dulles...
I also was on the same flight with Ron Artest once, but that was before he ruined the Pacers' franchise so I thought it was cool at the time. Nowdays if I saw him I don't think I would stop heckling him.