The audience. Absolutely the audience. People pay big bucks for Broadway shows, and DAMNED if they're not going to have a good time for their money, and SHOW you they're having a good time for their money! Some of the West End theatre programmes have articles, like Playbills, and I remember one article that had a section about audience reactions; the quote I remember went along the lines of: "directors would tell me they hadn't realised how funny their Chekhov or Ibsen was until they took it to New York". I'd love to quote a bit more of that article, but I have too many programmes to go through them all to find it.
I wish people realised you can have a good time and not be vocal about it. This is England for heaven's sake! We're meant to be the ones who sit in stony silence, only making noise at the end when we rise to our feet with thunderous applause! I'd love to go back to those days. ;_;
Yes, the play is a comedy. But not every line is a joke, so save your chuckles for when they're deserved. And if you're laughing during a non-comedy, you'd better have a DAMN good reason.
Can you tell I get angry with noisy audience members? ^_^