An easy way to confuse your audience is to use multiple pronouns. Instead of telling people that “Sally sold seashells to Melissa”, you say, “She sold them to her.”
Many presenters utilize stories in their presentations, which is a good thing to do. A problem that usually occurs is that the presenter knows the story so well, that the presenter oversimplifies the story by using pronouns. In my short example, it is confusing to the audience who she and her are and what was sold. This can be near impossible to catch for a presenter because the presenter is visualizing what is being said instead of merely listening to the story.
Another reason for this challenge is that many presenters do not practice their stories. In practice, when they get to the story portion of their presentation, they simply skip it because they already know the story.
A good way to prevent this is to practice with someone that does not know the story, possibly a co-worker or friend.