RIHANNA'S NEW BOYFRIEND IS NOT TOO HAPPY WITH HER FAN MAIL!

Rated R: Rihanna's rumored beau is none too happy about some very graphic fan mail his Barbadian babe has been receiving. "He's asked Rihanna's team to be extra-cautious since she was sent two very steamy letters," an insider says of RiRi's man, Matt Kemp. The source continues that the L.A. Dodger isn't the only one fretting over the songstress. Says the insider: "Her friends are really worried things with this guy are going to get out of hand."