Credit: DMac/Miguel/FameFlynet Pictures

Jennifer Lopez is walking on sunshine!

The 42-year-old American Idol judge and her new boy-toy Casper Smart spent Sunday playing with her nearly 4-year-old twins Max and Emme in Malibu.

As backup dancer Casper, 24, playfully lifted Emme into the air, Lopez showed off her impressive abs by tying up her long-sleeved shirt and dipping her toes in the water.

A mutual friend recently told Us Weekly Smart gets along "great" with Lopez's two children (with ex Marc Anthony, 43). "Jennifer wouldn't introduce him to them unless she know she could trust him."

Lopez -- who has yet to finalize her divorce with Anthony, her husband of seven years -- filmed a Kohl's commercial with Casper on Saturday. The clip was directed by Black Swan's Darren Aronofsky.