A producer of an off-Broadway show calls an out-of-work actor. He says, "One of my cast members just walked out on me. I need someone to fill in for him. I gotta tell you, it's a one-line part."
The actor says, "I don't care, I'll do it."
The producer says, "Great. You come on at the start of Act Two and say, 'Hark, I hear the cannon's roar.' I need you to start tonight."
The actor walks around his apartment saying, "Hark, I hear the cannon's roar. Hark, I hear the cannon's roar." He goes out to celebrate with his actor friends, drinks too much, and as a result gets to the theater late.
The stage door attendant says, "Who are you?" and the actor says, "I'm Hark, I hear the cannon's roar." The attendant says, "You're late. You better hurry and change."
The actor gets into costume and runs down to the makeup station. The makeup artist says, "Who are you?" and he says, "I'm Hark, I hear the cannon's roar."
She says, "Jesus, you go on in just a few minutes." She dabs on some makeup and pushes him into the wings. The backstage manager says, "Who are you?" and he says, "I'm Hark, I hear the cannon's roar." The manager says, "Well, guess what, the curtain's going up now -- you're on." He gives a push, and the actor walks on stage. There's a huge crashing noise behind him, and he says, "WHAT THE FUCK WAS THAT?"