TMZ has learned the 26-year-old long-haired wannabe's mane is actually a wig and it's got "Idol" execs flipping out. Sources tell us Robbie never talks about his matted down piece and that makes production members feel like it's the blonde elephant in the room. It seems Simon was right last night -- Robbie is a fake!
Where's Sanjaya's pony-hawk or Kat McPhee's extensions when you need them?!
A rep for "Idol" would not comment.