When you keep running into someone that you really don't want to run into, and it feels almost spooky or too weird to be a coincidence.
Erika: Wow, my ex-boyfriend just so happens to be going to an event that I'm going to tonight, AND he got a job in a city I used to live in, AND I saw him looking into my bathroom window last night.
Ethan: I think he's engaging in some textbook pseudo-stalking!