Yesterday I hung out some christmas lights onto our patio/balcony which faces Niederdorfstrasse. This morning I got up and our neighbour, I assume, had taken them down and thrown them on the patio. I assume its the neighbour as they had left a big sign in their window saying "DIES IST KEIN FERNSEHGERÄT, NO TV HERE!!!!!!!!!!!!" I don't really understand what he means by that, but the sign wasn't there yesterday so I assume its for us and its facing our patio.

Are you not allowed to hang Christmas lights? are there some regulations regarding this? I tried to find something on google but couldn't find any information.

I obviously don't want to cause any drama with the neighbours, but I found this quite rude...