Rihanna was "shocked" by the ballplayer's gesture, apparently expecting a small get-together with a few friends, a source says. She had no clue what her Boo had in store for her.
Matt had been planning the event for at least a month to make sure Rihanna's birthday was special, according to an insider.
There were flowers, Sprinkles cupcakes, tiki torches in the pool, engraved bottles of Ace of Spades and Johnny Walker Blue, as well as a Jamaican chef who whipped up lots of appetizers for the crowd.
Around 40 peeps showed up, including both Rihanna's friends and some of Kemp's baseball pals. Kemp brought out a cake decorated with the songstress' various tattoos, while everyone sang "Happy Birthday."
"It was so sweet and she was really surprised," the source said. "She looked just beautiful."Matt didn't stop his surprises with the singer's party, however. According to the source, he gave the birthday girl a custom diamond necklace.
Although the couple has played there relationship down, they reportedly spent the entire weekend together, first going out on Friday night with a group of 30 on a party bus to new Arizona nightclub Revolver, and then ending the weekend with a group brunch on Sunday.
