On Britney Spears
's 25th birthday, Dec. 2, the singer closely observed exotic animals, and the paparazzi observed Spears. The newly separated mom took son Sean Preston, 1, on a private tour of the Los Angeles Zoo, where they saw the chimp, zebra and giraffe exhibits (but zipped right past the hippos and black bears). "The [photographers] made it difficult," says zoo spokesman Jason Jacobs. "But everybody had a good time." Afterward, it was off for a quick bite of crab ravioli in lobster cream sauce at West Hollywood's Cravings and then next door, where the birthday mom pampered herself with a $6,000 faux fur from Just Cavalli. Then it was on to party animals. Spears hit Mr. Chow for dinner with pals and then headed to Hyde Lounge, where new BFF Paris Hilton
shared cookies and milk and presents and sang "Happy Birthday." (The Black Eyed Peas singer presented Brit with a birthday cake, while Hilton gave Spears a teddy-bear necklace and Kitson Kids goodies for her two boys.) "Britney was laughing and laughing and enjoying all of it," says a patron. "I've never seen her look so joyful." As the trio danced to tunes (including 50 Cent's "In da Club") on countertops until 2:30 a.m., Spears was serenaded—for the second time that evening—with "Happy Birthday." "The smile on Britney's face," says the patron, "was as big as the circle of friends around her."