When: May 2006 - May 2007

Soon after her high profile breakup from ex hubby Nick Lachey, Jessica Simpson rebounded with fellow musician Mayer. The two dated for nearly a year. On the 2007 Grammy Awards red carpet, Ryan Seacrest asked Mayer about his relationship with Simpson, but Mayer cryptically responded in Japanese. After their May 2007 breakup, Mayer famously dished about the couple's sex life in a notorious Playboy interview.

Smash Probability: Mayer's quoted in Playboy as saying, "That girl is like crack cocaine to me. Sexually, it was crazy." That pretty much says it all.