When teen heartthrob Justin Bieber appeared on a February episode of CSI, millions rejoiced, some at the fact that he's becoming a star on screen, others at the fact that he was shot dead on the episode. But not everyone was thrilled with his acting, especially not his coworkers on the show. Afterwards, CSI star Marg Helgenberger shared her thoughts with a French radio show explaining he was kind of a brat. "He was very nice to me. But he locked one of the producers in a closet, and he put his fist through a cake that was on the cast's table." Bieber took to his favorite outlet, Twitter, to fire back. He didn't mention Helgenberger by name, but the subject was unmistakable. And the message was rather mature for the 17-year-old: "It's kinda lame when someone you met briefly and never worked with comments on you. I will continue to wish them luck and be kind."