Jennifer Lopez Is Ab Fab!

2/7/2012 4:45 AM PST

Jennifer Lopez showed off her 42-year-old mother of two taut flat stomach while in Malibu the other day.

The "American Idol" judge was looking belly good, as her 24-year-old boy toy lover Casper Smart frolicked on the sand with her daughter Emme.

Ticking off Marc Anthony is like a day at the beach.