The 42-year-old went to the island of Kauai in Hawaii with her three-year-old twins, Max and Emme - her children with estranged husband Marc Anthony - and other family members, as well as dancer Casper, 24, to celebrate the annual holiday yesterday, according to UsMagazine.com.
A source told the website: 'Casper was great with the kids. He was twirling them around and doing flips with Emme and she seemed very comfortable with him.
'Jennifer got a chance to sit back and relax while Casper took over and played.'