Fellow speaker,
If you are telling a humorous story and no one laughs then your humorous story...wasn't...and everyone knows it! In those situations the tension is high, so it is the perfect time to use a "saver" line to acknowledge that the joke didn't work, to release the tension, and maybe to get a laugh anyway. Example, you tell a humorous story, come to the end of the story and no one laughs. You can then, pause, look around, see the lack of reaction and say, "That wasn't the funny part. The funny part is I actually expected you to laugh at that."
Saving the humor,
Tim
