The "nerd" pejorative isn't about doing well academically, it's more about bragging and obsessing. It's about making academic performance part of your identity. That's what people think is uncool. It's not like the quarterback loses points if he happens to be smart. He just shouldn't flaunt it or obsess about it.
I went through many schools as a child. I never bragged about my grades. Everyone always picked up on me being a straight-A student very quickly.
"Hey Teacher, how much is the curve on this test gonna be?"
"Well, it won't be anything because John got a 100."
[Angry glares at John]
This isn't unique to the Middle East. Its often no secret who the valedictorian of your class will be in my experience (American school)... even if the grades weren't revealed.
In any case, "Nerd" in my experience means something closer to the hobbies you persue. "Geeks" play video games and academically do good in "computer stuff" and music. "Nerds" pursue theater, LARP, and table-top RPGs (Dungeons and Dragons, Pathfinder, World of Darkness, etc.)
The intersection of "Nerds" and "Geeks" is anime, comic book heroes, and sci-fi.
Don't forget diminished desirability by those in whom one has a romantic interest (at least until well after adolescence). :)