A few more ideas that crossed my mind while sitting in a small dark space playing the cello:

The musical Titanic was heart wrenching and powerful.  Naturally all I could think about was how badass it felt to turn my own pages while playing.

I let my attention wander one night while playing The Gondoliers and stumbled upon this terrifying individual in the audience - who. never. smiled. once.

Or physically acknowledged a single joke.  

I was tempted to punch him.

Just to see if he moved.

Me and My Girl: I loved this musical.  Sometimes my affection for it was at the expense of professionalism.