Poindexter

According to the Oxford English Dictionary, Poindexter is slang for an overly diligent student or an extremely intelligent person. It's usually not intended as a compliment.

The origin of "Poindexter" comes from the 1950's cartoon show "Felix The Cat", one of the cartoons mentioned in the book. Poindexter was the overly smart nephew of the show's villain who helped Felix in his adventures.

Here's the Felix The Cat cartoon where Felix first meets Poindexter.