n. an underdog;
to pull a *, v. to do something miraculous; to wow or amaze a skeptical audience; to achieve success beyond initial belief or against the odds
She always surprises us. She's a real Susan Boyle.
pulled a Susan Boyle when she got a 1600 on her SAT.
"Did you see that girl on Top Model last night?" "Yeah, she was a total Susan Boyle!"