Only celeb I've had onboard was a rather unwilling individual - 4 people had to almost pull/push him onboard. Enroute he was kicking quite a lot, making funny noises, was not at all pleased with the catering and proceeded to crap all over the place. Someone paid him 500K Euro for a single performance at the German Grand Prix, and we got to fly him back and forth on a charter.
Ah well, when you're a GBP 10M race horse called Mahmoud, is worth more than the aeroplane, and is employed by the Gadolphin stable, I suppose most things go. At least he didn't kick me, the smelly bastard.