"They've opened a lot of doors for me, these hands." is one example. I think that's the funniest line ever, but it's in a new place in the script, and clearly the audience is listening or focused on something else, so they are unable to process a pun.
One of the most interesting parts of coming so many times is to hear the response of so many different audiences. Every audience is unique in its collective response. We have had audiences that laugh at every line, audiences that don't laugh as often but louder when they do, audiences that gasp at shocking or mean lines. I'm sure the actors are putting out different energy each night as well which add to the mix, but there is really a compelling, individual identity that forms within an audience that is bizarre and mysterious, and the performers respond and adjust to it. That is one of the most fun parts of coming again and again.
I was talking with Tracy too about how fragile comic timing is. A slam dunk line on any other night can get completed diffused by the slightest stutter. Once, John K. had the tiniest hiccup while saying "Caldecott Tunnel" and nobody laughed at the following punchline, which normally gets a huge response. Weird! Interesting! Wow! What a mystery this theater and comedy is! (It's just an example, John, sorry!) When a joke that normally gets a laugh doesn't, often the following joke becomes huge, when it normally only receives a chuckle.
So, I'm a nerd about this.