Where's her top? Someone in wardrobe is getting so fired over this.

Justin Timberlake has been dumping Jessica Biel for a few years now (see here, here, and here), so it's not really that shocking to hear that he's messing around with chicks behind her back. What is shocking is how satisfied I am after eating this Snickers bar. I thought it was just a slogan . . . From Us Weekly:

Justin Timberlake cheated on Jessica Biel with actress Olivia Munn during a three-day fling this past September, reports the new Us Weekly. Timberlake, 29, and Munn, 30, a Daily Show correspondent who stars in the upcoming NBC series Perfect Couples, first met at a Sept. 26 MySpace event.  After exchanging numbers, he "started chasing her immediately," says an insider.

Munn resisted his advances, telling him it was a no-go if he was still with Biel, 28, the source tells Us Weekly. But Timberlake "has been telling people it’s over with Jessica, even though "the reality is he's just doing it behind her back."

Believing he had left Biel and that her relationship with Timberlake might develop into something serious, Munn took him to her hotel, the Gansevoort Park Avenue NYC, Sept. 27 and 28, where "they were openly affectionate," the insider adds.

The insider tells Us the two "had amazing sex" that night.

Justin should be ashamed of himself. Lying to get a woman to sleep with you is just appalling. It's why when I go clubbing, I don't actually tell women I'm a doctor to get them to go home with me. Hey, if a drunk chick wants to jump to conclusions because I'm wearing full scrubs and a stethoscope around my neck, that's on her. I didn't say it.

*22 Olivia Munn pictures total in the gallery: