There is no one answer to this question as different narcissists will have different things that make them miserable. However, there are some general things you can do to try and make a narcissist unhappy. For example, you could ignore them or give them criticism instead of compliments. You could also try to humiliate them in front of others or make them feel like they are not important. If you know what specific things trigger the narcissist's insecurity or anger, you could use those against them as well. Ultimately, though, it is important to remember that trying to make a narcissist miserable is likely to be an exercise in futility and may even backfire on you.