Casting aside her new good-girl image to enjoy wild benders and sneaky sex romps with ex-hubby Kevin Federline, Britney Spears has transformed herself into a modern-day Jekyll and Hyde — picture-perfect by day and a crazed party beast by night, NW reports.

Britney Spears enjoys wild benders and sneaky sex romps at night?

Despite looking happy, healthy and more stable than ever as she enjoys low-key lunches and daily gym sessions, insiders say Britney Spears, 26, wastes no time in breaking loose whenever the eagle eyes of dad Jamie are turned.

"During the day she's dressing down, going to the gym, drinking protein drinks and taking her medications," says a source. "At night she's dressing sexy, smoking heavily, drinking high-energy drinks and having private gatherings at her home as Dad leaves."

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