Britney melted down in such a dramatic fashion that it’s set a precedent for all those who have followed her (take note, Miley Cyrus). Looking to shake off her Disney-clean image, she first pushed the boundaries of just how raunchy a video could be and then she lost it completely. She shaved her head, on camera, and allegedly took an overdose of amphetamines. Apparently, the two were linked, as Spears was paranoid that traces of drugs would be found in her hair and her children would be taken away from her. Rehab swiftly followed, along with whirlwind romances and patchy chart success, but she has since calmed down, with a stint as a judge on the “X Factor” and a new album coming out soon.