Jenni's pronoia convinced her that small pixies were out to sprinkle her with fairy dust and feed her cookies.

Phil thinks that he is indispensable at work and that his superiors and colleagues adore him. Sadly, this is a case of pronoia since he is totally incompetent.

or

Melanie has a case of pronoia because she thinks everyone looks up to her, when in reality, people think she's quite obnoxious!