To make a hilarious narrative you must have, first of all, have a funny story no one wants to spend time listening or reading something not funny. Second, you need to have a narrator or something to make the story to come to life. Third, probably don't take a joke off the internet or from a comedian you like, if you are having trouble finding a joke, look at everyday life. Fourth, know who your audience is they might be offended by some stuff you say or do. For example, my joke has some offensive stuff to mid eastern people but my audience are school kids so they wouldn't be offended by my joke. Finally, if you need to, practice on other people.
My comedic monologue is about my family almost being scammed by some Middle-Eastern and my mom wanting revenge on those people. My comedic monologue is funny because it puts in dialogue which is that hilarious indian accent. It also sees how parents are so protective over there families and what they will do to protect their families, and also to make their families laugh.