Michael Kors Black Friday Sale A sure sign someone made it in show business? A feud with another celeb.The 17 years old pop star Bieber recently guest starred on an episode of "CSI: Crime Scene Investigation," and apparently his work didn impress the show stretch of time star Helgenberger.As outlined by reports from AOL Hollywood gossip blog, PopEater, Helgenberger told a French interviewer that Bieber must have been a "brat."Though she also said she only enjoyed a small scene with Bieber, his apparent inappropriate behavior on set really lead to her consensus. From the interview, she said Bieber "locked a producer within a closet," and "put his fist using a cake within the cast table."The famously coiffed singer has sounded off about Helgenberger comments on Twitter. Though he didn name names or point fingers, Bieber tweeted, "Its kinda lame when someone you met briefly and d