The public fascination with the sex lives of the rich and famous will never cease, more so than ever with tabloid culture keeping a track of every cuddle, snog and hotel room reservation. Yet, somehow, a select few celebrities have managed to keep their relationships a secret over the years. Take for example our cover photo, number 15 on our list, the gorgeous Cameron Diaz and handsome Robbie Williams. The Hollywood actress was spotted in a clinch with the UK singer on Santa Monica beach in 2003. Robbie even took her on a date that involved the ever-romantic activity of go-karting. Obviously this relationship didn't last too long. We can't help but to imagine that the whole thing was 'Something About Mary' style madness.