We all know rappers diss each other in songs all the time. But what about rockers? Nikki Sixx claims that Bruce Dickinson wrote "Tattoed Millionaire" about him after he banged Bruce's wife. He was also the target of Godsmack's "Crying Like a B*tch." Pink has taken shots at the pop princesses she was compared to early in her career in songs like "So What?" (Jessica Simpson) and "Don't Let Me Get Me" (Britney Spears). Any others?