Two bass players were engaged for a run of Carmen. After a couple of weeks, they agreed each to take an afternoon off in turn to go and watch the matinee performance from the front of house.
Joe duly took his break. Back in the pit that evening, Moe asked how it was.
"Great!" says Joe. "You know that bit where the music goes 'BOOM Boom Boom Boom'? Well there are some guys up top singing a terrific song about a Toreador at the same time..."