I can see some CW executive pitching ideas for the story right now.
"Ok we need a teenage girl. One that's pretty but not too pretty, one that other girls can relate to. Now she wakes up in her homeroom with the exploding collar on . . . yeah you're right it can't explode, it will just poison them. No, not like cobra poison,the kind of poison that makes them just fall down. Yeah that's perfect Johnny, it's an overdose of tranquilizers!"
"Anyway she wakes up and looks around. First she looks around the class and then out the window. Across the way she sees another classroom full of passed-out students. No they aren't from her school. So she sees someone awake in the other room. He's tall, dressed in black and has long black hair. Well the werewolf Indian guy from Twilight had long hair. Have an intern go through the recent teen magazines and count the different hair styles. No don't count Beiber. Forget his hair for now, just know that he's dark and broody. He looks over and sees her; He looks in her eyes for only a second before looking away. And in that second she knows that they could either love each other or kill each other. No she can't internal monolog that, we don't want to get SUED by the Twilight people."
"Now someone else wakes up in her class and starts talking to her. It's the Quarterback of the Football team. Soccer? Ok then we'll make him whatever is important on a Soccer team. He's talented, popular and smart. He has never said anything to her. Secret crush? Him for her or her for him? Both? What a bold idea, I like the way you think Johnny!"
"Well first he will get her attention and then he'll will say,'You know what this is, right? This is . . .' AND THEN WE WILL FLASH TO THE TITLE CARD! BATTLE ROYALE! The words will be dripping with blood. No I'm sure we can use blood there. But that will probably be it for the blood."
I'm gonna stop doing this now because I'm actually getting annoyed by what I'm writing and at the same time I'm terrified that I'm able to write it.