The 'On The Floor' singer was joined by her 3-year-old twins Max and Emme as well as Smart for a Turkey Day celebration on the island of Kauai, according to Us Weekly.
An insider revealed details of Lopez's beach trip with her children and Smart, telling 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."
Lopez has remained coy on her apparent romance with Smart since they were first spotted on a series of dates earlier this month.
The American Idol judge refused to speak about her private life during a recent interview with Ryan Seacrest.
Lopez said at the time: "I told everybody at the end of the day, until I am in a really serious relationship, because of the babies, I'm not really going to be commenting on my personal life."
She filed for divorce from husband Marc Anthony in July after seven years of marriage.
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Watch Jennifer Lopez's 'On The Floor' music video below: