This is sio relelvant to me that I thought I might be the neighbour for a moment! My neighbour's foster boys - both 17/18 sit outside their house, directly under our bedroom window to smoke & talk. It really disturbed us even though they weren't rowdy just talking quietly. After a few sessions I went round and asked my neighbour if the boys could avoid doing it after 11 at night. I also added that we could hear everything in the conversation including the phone numbers of who they intended buying their drugs from that weekend. The boys are rarely there now! My point is that it really was a problem as once they were outside talking & we were in bed, we had no control over the situation and had no idea if they would get noisier, go in, stay out etc. Even though your neighbour sounds not nice, I understand his point of view.