Saw Blue
When someone says they "saw blue" when referring to Guitar Hero, it's usually to the song Jordan by Buckethead. When on Expert, at around 60% of the song, a blue starpower note comes up and it's easy to get. Many people agree that after this part of the song, the rest is easy to complete.
"I was just about done with the main solo of Jordan, and I saw blue, but I failed before I got to the note."