Well, that's what happened to Al Moseley on the set of the recent Prince's Trust ad about saving the rainforests.
Apparently, the Dalai Lama took umbrage with Moseley's need to get the take just right and became agitated at having to redo the shot where he is talking to a frog.
His anger was exacerbated by the fact that, for the shoot, the frog was a beanbag and because no-one had thought about supplying frog noises, Moseley himself was talking to the Dalai Lama in ribbetts.
Diary's spy on the shoot reported the conversation like this:
Dalai Lama: "If you make me do it again, I'll throw it (the beanbag) at you."
Moseley: (In between making frog noises) "You have to do it again."
Dalai Lama: "You have made me angry."
The Dalai Lama's monks: "You have made him very angry."
And he wasn't the only one pissed off by the shoot - apparently, when Calista Flockhart walked into the living room in the house she shares with Ford and saw him sitting talking to a beanbag in front of the camera, she rolled her eyes and flounced out.