Mila Kunis, Justin Timberlake Sexual Act at MTV Movie Awards (PHOTOS + VIDEO)

At the MTV Movie Awards stage in California, the audience were shocked by Mila Kunis and Justin Timberlake demonstrating how to be Friends with Benefits by sexually groping each other before presenting Robert Pattinson with Best Male Performance award.

The two actors gingerly grabbed each other while explaining the relationship was purely platonic -- Timberlake grabbed Kunis's chest, while Kunis reached back and grabbed Timberlake's crotch. And the two, thus occupied, presented the nominees. The two have denied any speculation that they are dating.

Even though we're in the movie Friends With Benefits, Mila and I have never dated, Timberlake told MTV Networks. Mila then agreed: We are like brother and sister, before Timberlake added: We have a totally platonic relationship, which is why I can do this - grabbing Kunis' breasts. In return, Kunis grasped The Social Network actor's crotch, also claiming: This is why I can do this!

It’s not always a bad thing to have sexual chemistry with your mother, joked Pattinson, who has played Witherspoon’s son and love interest in two movies, as quoted by the New York Post.

Friends with Benefits, which will hit theatres on July 22, follows a young couple who meet but are too busy to begin a romance instead agreeing to have an intimate relationship with no strings attached. The movie is directed by 'Easy A's' Will Gluck, and also stars Woody Harrelson and Patricia Clarkson.

This wasn't Timberlake's first brush with live TV and a breast, the Baltimore Sun reported. In 2004, Timberlake ripped off one of Janet Jackson's chest plates during the Super Bowl halftime show, leading to a massive controversy and the coining of the phrase wardrobe malfunction.

Take a glimpse of Justin Timberlake and Mila Kunis groping each other, and Timberlake pulling off one of Janet Jackson's chest plates: