Jennifer Lopez Flaunts Amazing Abs in Sexy White Bikini

Jennifer Lopez and Casper Smart take her adorable twins Max and Emme to the beach in Rio de Janeiro on June 25, 2012. Credit: Honopix;

Jenny from the Block hits Brazil!

Jennifer Lopez spent time seaside in Rio de Janeiro with her love Casper Smart, twins Max and Emme, 4, and a group of friends on Monday.

Donning a sexy white two-piece for her day in the sun, the American Idol judge, 42, showed off her amazing figure -- including her toned abs -- in a white halter bikini top as she frolicked by the water with Smart, 25, and her children with ex-husband Marc Anthony. (Max and Emme kept busy with a very important project: burying a family friend in the sand.)

Though they've only been together since Fall 2011, Lopez's relationship with her backup dancer has already gotten serious.

"She's telling friends she wants to marry Casper," one insider told Us Weekly in May. "She's certain she wants to be with him forever."