Jennifer Lopez's friends threw her a surprise birthday party on Tuesday (24.07.12).

The former 'American Idol' judge's pals including Mary J. Blige, her manager Benny Medina and boyfriend Casper Smart celebrated her turning 43 with a lavish bash on the yacht Utopia III, which is owned by Market America co-founders JR and Loren Ridinger.

A source told the New York Post newspaper: ''J.Lo got out of her car blindfolded and took it off when the guests yelled 'Happy Birthday' over the side of the yacht.''

Jennifer - who has four-year-old twins Max and Emme with former husband Marc Anthony - then boarded the yacht and after guests sang 'Happy Birthday', she blew out the candles on a cake in the shape of a giant teddy bear.

She was then thrilled with a gift from Casper.

Her 25-year-old lover presented her with a diamond necklace featuring a Pink teddy bear, a reference to the term of endearment, ''bear'', that the couple use for one another.

Afterwards, Jennifer jumped behind the bar and poured shots of Patron tequila for the guests before embarking on an ''intense, hot'' salsa dance-off with her friends.

The party went on until 4am, with DJ Ani Quinn and DJ Prostyle's choice of music proving a hit with guests.