Never knock on the door. That’s how horror movies start. Instead, slide a note under their door, written in a font that screams "friendly, but I know where you sleep." Something like: "Hi! Your bass is shaking my family photos off the wall. Could you lower it? Also, please stop breakdancing at midnight. Thanks!" It’s passive-aggressive, but it gives them a chance to save face. Surprising fact: Studies show that 70% of noise complaints are solved by a simple note. The other 30% are solved by moving to a monastery.
If they ignore the note, escalate to the classic baked goods strategy. Deliver cookies with a printed warning on the tin: "These are not laced. But my patience is wearing thin." It’s disarming. They eat a cookie. They feel guilty. They turn off the techno. You are a genius.