What does the cheerleader say to Lucas Till during football game on Taylor music video You Belong With Me?

The cheerleader in the "You Belong With Me" music video doesn't actually say anything to Lucas Till. The scene you're describing features the cheerleader (played by JoJo) giving Lucas Till a look of jealousy and resentment as Taylor Swift sings about how she wishes she was dating him.

While the scene is full of unspoken tension, no words are exchanged between the cheerleader and Lucas Till.