The act of being new to guitar hero and being afraid of the blue and orange frets because you don't think your pinky finger can take it. The normal reactions to this are anger, threats, violence, and, depending on how drunk the player is, incessant giggling. Symptoms may include reluctance, making up excuses not to play, and headbanging to draw attention from the T.V.
Danny: Oh crap... here comes the solo...
Everyone watching: *laughing*
Danny: Crap! I told you guys I had Fretaphobia! I'm NEVER PLAYING AGAIN!