In Cartoon Network bumper dance why did the girl get hurt?

You're likely referring to a popular meme that involves a specific Cartoon Network bumper, but there isn't any official information about the girl getting hurt. The meme humorously portrays the girl in the bumper as getting injured, but it's all in good fun and not an actual depiction of the animation.

Can you provide any more context? Perhaps you can describe the bumper you're referring to or the specific meme you've seen?