Mila Kunis & Justin Timberlake joint appearance on Ellen DeGeneres' TV show: The actors, both of whom have recently ended long-term relationships, were promoting their new movie Friends With Benefits - although they insisted such arrangements never work out in reality. 'It's a really good idea until it becomes a bad idea,' Timberlake said of friends who have casual sex. 'And it probably becomes a bad idea really fast.'

As for the nudity in the movie, Kunis said: 'It's as comfortable as something like that could be.'As for working with an often nude Timberlake - who says he 'wore a sock of some sort' while filming - Kunis joked: 'It's really hard work - every morning I have to go to work with him, it sucks.'Ellen later had the actors play a charades-style game.