JENNIFER LOPEZ puts the muzzle on toyboy CASPER SMART as she makes him sign a NO KISS and TELL ALL.

She made much younger lover Casper ign a confidentiality agreement because not only is he her lover but he's also J.Lo's employee, reported.

"Casper signed a non-disclosure/confidentiality agreement when he began working for Jennifer Lopez, as she requires all of her employees to do." a source told Radar.

“Casper and Jen began dating several months after she separated from her third husband, Marc Anthony. The confidentiality agreement covers all interactions that her employees have with Jen, including anything that occurs off the clock.

"Jen has been around long enough to know that anyone she dates could possibly turn on her and choose to go to the press if the relationship sours. Casper had absolutely no qualms about signing the agreement, and has told Jen on multiple occasions that even if he didn't work for her, he would have signed the contract.

“Jen loves him even more for THAT."

And for good reason — J.Lo has had a long-running court battle with ex-hubby Ojani Noa, Radar pointed out.