All of this is ALLEGEDLY. Few weeks ago a car parked behind mine and scratched the back part of my car (I know it was him because he left his car hitting my car plate without space between the two cars). I left a note in his car to contact me, the only thing I wanted was an apologize, that's all. He called me useless, told me that I can't park and he hung up the phone, so I send the pictures of how he was parked to my insurance. A proficient determined that the fixing would cost 200€. His insurance said that if I want to get my car repaired by them I need to hire a lawyer etc... too much for scratch, honestly.
Here is the thing, he studies in an institution next to my house and he knows where I live because he saw me entering my house (and since that day every morning someone ring the doorbell for 20 seconds mmmm).
I need ideas to ruin his car a little in a way that he can't notice immediately. I don't need something crazy, only a little revenge for his behaviour. I've also have his phone number (but he has mine so it's risky). Any ULPT? Thanks.
EDIT: Thanks so much for your suggestions, I'm in the right place (you are diabolical). These are my favourite ones:
-Deflate the tires: the bb tactic is good but he will notice the sabotage. The ice hack is genius but it's not that cold here to be effective.
-Sticky windshield: this has a lot of potential because in this street there are trees that exude a sticky substance so he will blame the trees for that.
-Putrid liquid into air vents: really juicy but I'm not a monster.
-Ruin the car paint: this could be great but I have to test which chemical is the more effective.
So after thinking the pros and cons this is my plan: I'll wait until January so he will forget our fight. I'll mix water with sugar and I'll spray it all over the windshield. It's hard to clean, attracts bugs and not that suspicious. I'll share the updates with you, comrades.