Jennifer Lopez received a diamond necklace with a pink teddy bear from her 25-year-old boyfriend, Casper Smart, at her surprise 43rd birthday Tuesday night. Sources told us “bear” is the term of endearment the lovebirds use for each other. Lopez was surprised by friends including Mary J. Blige, her manager Benny Medina and Smart at Pier 60, where her pals had gathered on the yacht Utopia III, owned by Market America co-founders JR and Loren Ridinger. “J.Lo got out of her car blindfolded and took it off when the guests yelled ‘Happy Birthday’ over the side of the yacht,” said a source. The mother of twins then joined her guests onboard and blew out the candles on her cake in the shape of an oversized teddy bear. Afterward, J.Lo got behind the bar and poured shots of Patron for other guests. She then embarked on an “intense” and “hot” salsa dance-off with her friends and dancers on the floor. DJ Ani Quinn and DJ Prostyle spun tunes for the party, which we’re told went until 4 a.m.