a person who is well-versed in general knowledge. also refers to the general knowledge category of the board game, Cranium.
A: what does DNA stand for?
B: don't ask me, ask that guy. he's the datahead.
(baseball) Refers to Pedro Martinez. His pitching was good enough that baseball players, pundits and other fans need only refer to him by his first name to understand the notoriety behind the name.
Damn, the Braves are facing Pedro tonight.
The Red Sox are sending Curt Schilling to the mound tonight. Pedro will start tomorrow.