Seems like Rihanna is having a bit of fun since her break up from Matt Kemp back in December. According to US Mag, the singer has been hooking up on the down-low with none other than Reese Witherspoon's ex husband, Ryan Phillippe:

"They initially hooked up when things were strained with Matt Kemp back in early December. She thinks he's hot. They totally had sex. And it wasn't even the first time!"
Ryan's last conquest was initially rumored to have been Amanda Seyfried, but guess he couldn't resist the opportunity to grind with the sexy Barbados beauty!