A gig is simply not complete until somebody falls over the monitors. In the bands I play in, we have even fitted angle jacks on them so our gear does not get damaged!
Man, my little brother sang at my wedding.
My fiance and I were not at all sure that it was a good idea because we laughingly remembered how horribly (and I mean horribly) he used to sing when our rooms were seperated by a single wall.
But, apparently in the four years after I moved out he learned a range.
It was probably the single happiest moment of my life and he nailed it.