I wonder snippy remark Blair Waldorf will have to say in reference to Lady Gaga when the often pant-less singer makes her appearance on Gossip Girl. The singer has just filmed an appearance on the Lower East Side for an upcoming episode. No word on what her appearance will involve – yet. Will Serena or Georgina be her new BFF? And how many more guest stars will the Gossip Girl producers lure in to ensure we all keep tuning in? [NY Daily News]