Jennifer Lopez's hunky young boyfriend / backup dancer, Casper Smart, celebrated his 25th birthday on Friday, and Lopez, 42 was front-and-center of the birthday festivities, as was the brand new, customized white Dodge Ram truck that she bought him.

"Jennifer had planned a fun day to celebrate Casper's birthday," a source told People, and she "knew that Casper really wanted a truck." So Lopez surprised Smart with the massive gift. "Casper was so excited about his new truck," said the source.

Afterward, Smart and Lopez took the new wheels out for a spin on their way to dinner at Cecconi's in West Hollywood. Lopez also tweeted about her boy-toy's big day to share her excitement with her Twitter followers: "@BEAUcasperSMART 'Beau has a birthday we're so glad we hope its the happiest Birthday Beau ever has! #singingtweet. HAPPY BIRTHDAY BEAR!!!"

Smart later replied to Lopez in his own text. "Thank u all so much for the birthday wishes, I really appreciate them and u!!! :)"