The general guideline is to pretty much play with the severity of the level. If it's so severe and been one-sided and very unfair to your perception from the other person then might as well even out the odds by doing something very tacky but capricious and making others a little concerned about how smart you are.
Here's another thing to keep in mind; it's worthwhile approaching her and trying to communicate with her and getting through her negative games she's playing, if the guy actually finds her cute. Always communicate with the thought of trying to help her and bring improvement on her life, even if it's just making it up. If she's going to say that you're harassing her then just play it like you are selling yourself with helping her.
Overall, if it's a repeated pattern and you clearly are aware of what you are saying, keep it nothing negative and nonthreatening. Don't even make sarcastic jokes about very negative things happening. Keep everything optimistic and then state clearly you are not harming her. If the pattern keeps going on, and she's not reporting you to the cops or anything and it's been going on for years where she just hangs up on you even though she's been threatening to do so like blackmail or just shuts down with you, don't up the ante and go stalking her, you are on the right page. Finally, pay 100% in detail to the girl and be sure to really like her even when you didn't all those other years.
