another one I remember was as a kid I saw Cybil Shepard in a summer stock tour of Lunch Hour. The lights kept flickering and she kept trying to continue. It happened about four times and then finally she just put her head down on the table and had a laughing fit that she couldn't seem to control. The audience always seems to enjoy stuff like that and there was a round of applause and then they eventually slowly worked their way back into the show.
