There are a few possibilities for why you might be thinking this:
* Misremembering a different book: It's possible you're thinking of another book with a similar plot.
* Mixing up characters: Perhaps you're thinking of a different character in the *Percy Jackson* series who was attacked or harassed, but not by cheerleaders.
* Fanfiction: There are many fan-made stories and adaptations, and some of these might include scenes with cheerleaders attacking Percy.
Could you tell me more about what you're thinking of? Perhaps you can remember the book title, a specific detail of the scene, or the character who attacked him? I can then try to help you figure out where this idea might have come from.