Why is the blonde always mean?

Have you seen Mean Girls? I caught a part of it this weekend.  It's one of my favorite movies.  Tina Fey is an absolute genius. But one of the things that bothers me about the movie is the stereotype that blondes are mean.  It's not just Mean Girls.  Young Adult literature is filled with blonde characters that are heartless, cruel, and by some illogical twist of fate, also popular.

So here's my blonde anonymous confession. *stands up* My name is G. P. Ching.  I was a natural blonde in High School and I was a nerd.  I was not popular.  I was not mean. I was, however, wicked smart and opinionated.

Guess I didn't fit the mold, huh?

Here are some other stereotypes that I find comical in YA literature.

1. The heavy girl is always sweet.
 BAH!  I knew lots of heavy girls who were really mean and made it their life's mission to tear down anyone they felt was better than them.

2. The minority is the outcast.
Uhm...Our class president was a minority and my school was 98% white.

3. Attractive girls are cheerleaders.
Not so.  Today, the athletes that make the cheer squad are the ones who can tumble, have rhythm, and lead the crowd.  Last I heard, beauty wasn't on the scorecard.

4. Asians are brilliant.
Well, this one is mostly true. LOL!

So why do you think these cliches persist?  Which ones make you laugh? Are there ones I haven't mentioned that are your personal pet peeves?