Public Speaking Course:
Using a callback is a good skill you will learn in my public speaking course. It means to refer back to a word or phrase you mentioned earlier in your presentation.
A Callback can work well whether the previous material got a good laugh, or received a bunch of groans. If the previous material had a good reaction, mentioning it again will create more laughter and will make you look good for being able to tie the previous material to the present.
If the previous material had a bad reaction, the callback will show your willingness to make fun of yourself, which is an admirable quality the audience will appreciate. A true professional having been through my public speaking course knows when he does well and when he doesn't. He can laugh at himself and learn from his mistakes.
Here's how to make it work for you: Let's say you used a successful two-liner in your presentation 'Don't rely on health books too much. You could die of a misprint'. Later in your presentation someone might notice a misspelling in one of your handouts or visuals. You can then 'call back' and say, 'See, that's one of those misprints I was telling you about earlier.'
Another thing that could happen, that is just as good, is someone from the audience might make the connection and do the callback for you. One of them may blurt out something about your health book line. Laugh along with them, because you are getting them involved and allowing them to feel superior to you, which makes them feel like the star of the show. Participation is part of audience attention and is an important skill to focus on while in your public speaking course.
You could then come back to the callback with, "See, I put that there to test you." When you really get confident, you might actually make the misprint on purpose to set up this whole scenario