I'm ready to take all the negative XP's, but IMHO, there is a single worst thing to spoil my day:
Playing U2 or Coldplay on public radio
It makes me so very very angry. It ruins my day. Currently all public stations play top-2000 or something like that, and the overwhelming amount of ether-pollution in it makes me change station all the time.
Happy new year, and please please enjoy whatever music you like. Just don't force the shit on me