This Will Sound Shallow But...
...I think they should have casted uglier people as the nerds.
I mean, the main guy and the skater looking nerd probably wouldn't have been bullied in real life, and based on looks alone probably would have found themselves in a more popular social circle growing up.
Now, before anyone jumps down my throat, I have low tolerance for bullies. I can't stand bullying. But I'd say statistically, those who are bullied generally have something about them that sets themselves apart from their peers, whether it be because of wardrobe, intellect, hobbies, activities, body type, etc. I just can't really see the "nerds" in this movie (aside from the girl) being all that different (not counting personality wise, given they were not bullies before they decided to do what they did).
It's like when they cast a hot girl to play an "ugly nerd" (like in She's All That or A Walk To Remember). It's not realistic at all.
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I don't put movie quotes in my signature.