The speaker usually thinks of setting up a punch line as part of telling a joke. But the speaker can also set up a punch line in the opening for later in the presentation in order to move people to action.
I was in an audience recently where the speaker ahead of me had opened his talk on family relations by mentioning that he had seven children. He went into detail about their ages and that the youngest one had just had his first birthday last week. He then pointed to the picture of each child in the family photo on the screen and gave his or her age, ending by pointing out that he had four boys and three girls. He talked a little about their daily routines and this was certainly pertinent since the narrative gave him credibility to talk about family.
I did not realize, however, that this personal information was also setting up a punch line for his conclusion. As he moved toward the end of his talk, he referred to the table in the exhibit area containing books and programs available for purchase. He described the content of each and paused. Then in a serious and deliberate voice he said, “I want you to know that all proceeds go to feed hungry children.” He paused. “Seven hungry children.” Of course the audience remembered the story early in the presentation and laughed at this remark. He was able to motivate people to buy his product without seeming to be hard-selling his audience.
This example also illustrates that there are other contexts for which the set-up can be applied. When preparing your next speech, don’t limit your introduction to simply getting the attention and previewing your presentation. Consider what you might say that would set up a move-to-action statement in your conclusion.