Justin Timberlake may be promoting his new flick 'Friends With Benefits' but the star admitted on 'The Ellen DeGeneres Show' that the reality of the concept often ends badly.

"It's a really good idea until it becomes a bad idea. It probably becomes a bad idea really fast," he said.

According to RadarOnline.com, Timberlake and his co-star Mila Kunis dropped by a taping of the daytime talk show to discuss the premise of their new movie where their characters decide to hook up without the constraints of a relationship.

"I think that everybody could probably agree with us when we say, that if you're going to be intimate with someone at some point somebody's going to feel something," Timberlake said of the concept, though Kunis remained quiet on the topic.