It turns out Britney Spears is really into "S&M." Who knew? The pop princess paired up with Rihanna this week for a remix of RiRi's mega-hit and even got her own verse in the song. Rihanna told the Z-100 radio station in New York she was looking to do something "major" with the mix and her fans wanted Britney. But that's not all that's going right in Brit's life: She also found a replacement act (remember when Enrique Iglesias dropped out a few weeks ago?) for her upcoming "Femme Fatale" tour -- Nicki Minaj.Britney Spears, credit: Max Morse / Getty Images; Rihanna, credit: Jae C. Hong / Associated Press.