Never announce the joke or story with lines like: "A funny thing happened on the way here...", or  "Do you want to hear a really funny joke?", or  "That reminds me of a story...", or  "Have you heard the one about...?"

Lines like that give the audience an expectation,  and the eventual story or joke might not live up  to that expectation.

If you announce or pre-empt, and if the tag or the  punchline isn't strong enough or doesn't provoke a  laugh, you'll "die" on stage.

If you simply slip the story or joke into the presentation,  and the audience doesn't get it, just continue as if you  weren't devastated by the lack of response.

If they don't understand the joke or don't see the  humour in your story (and what could be more deflating  than total silence after you've delivered the tag?), don't say: "You must be out there; I can hear you breathing", or  "Is this an audience or an oil painting?", or
"You don't get it now, but later when you're driving home,  you'll get it and you'll just crack up laughing", or "I'm doing comedy over there and tragedy over here", or  "You had to be there", or  "This is the first time I've given a speech in a wax museum".

Why wouldn't you use these? Comments like this are normally made in a moment of desperation when the presenter is struck by the realization that it's not working, so it's easy to put the audience down. The problem is that the attendees, en masse, could turn
against you. A more appropriate and endearing reaction  would be to put yourself down with a comment like:  "Well, I'm glad I told THAT one."

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