An out-of-work actor gets a call from his agent one day.
"I got you a job. It's a one-liner."

"That's okay!" replies the actor, "I've been out of work for so long I'll take anything. What's the line?"

"Hark, I hear the cannons roar," says the agent.

"I love it!" says the actor. "When's the audition?"  "Wednesday," says the agent.

Wednesday comes and the actor arrives at the audition. He marches on stage and shouts, "Hark, I hear the cannons roar!"

"Brilliant!" says the director, "you've got the job! The first show is at 9 o'clock, Saturday night."

The actor is so excited that he goes on a major bender. He wakes up 8:30 Saturday evening and runs to the theatre, continually repeating his line, "Hark, I hear the cannons roar! Hark, I hear the cannons roar!" He arrives and is stopped by the bouncer.

"Who the heck are you?"

"I'm Hark, I hear the cannons roar" says the actor.

"You're Hark, I hear the cannons roar?" says the bouncer. "You're late! Get up to makeup right now!"

So, the actor runs up to makeup. "Who the heck are you?" asks the makeup girl.

"I'm Hark, I hear the cannons roar!" he says. "You're late! Sit down." So she applies the makeup. "Now,
quick, get down to the stage, it's almost time to say your line!"

So he dashes down to the stage.  "Who the heck are you?" asks the stage manager.  "I'm Hark, I hear the cannons roar!" he replies. "Oh, thank God! Just in time! Now get out there, the curtains are about to go up!"

 So, the actor runs onto the stage. The curtains rise and he sees that the house is full. Suddenly, there is an almighty bang behind him, and the bewildered actor shouts,

"What the fuck was THAT?!"