Calvin Klein has provoked controversy with his latest billboard ad in the US. Unveiled in New York, the ad shows a topless teenage girl lying on a bare-chested man and kissing a second. But the image hints that the threesome is going to get even more complicated as a third man looks as though he's about to join in too. The American Decency Association is calling the ad "degrading" and is urging consumers to call Calvin Klein's CEO and complain. New Yorker Jon Rose who was walking down the street with his 11-year-old daughter, says he thinks the ad goes too far. "I was thinking there's a fine line between sexy and obscene and I think they've crossed it. I'm not a prude but it's not appealing to me." Calvin Klein is no stranger to controversy. In 1981, a teenage Brooke Shields announced "You wanna know what comes between me and my Calvins? Nothing."