What are some of the funniest things either a volunteer or a member of the audience has said or done during one of your shows?

I think the funniest I have to date is a show I did at a costume party. Part way through the show, I took my sword out of its case, and someone dressed as William Wallace stepped forward and challenged me to a sword fight. He did it perfectly and it got a better laugh than anything I'd done the entire night - I wish I could arrange it for every show

I'd be interested both to hear the funny things your audience have done, and also if you've managed to somehow make it a part of your show.