"Let"s hit the gym tomorrow!" Shirtless Jason Dundas flashes six pack and challenges new Calvin Klein model Justin Bieber to an "abs-off" One is an Australian host and the other a 20-year-old US singing sensation - but both are abs-sessed with the gym. And now that US singing sensation Justin Bieber has packed a punch as the latest model for Calvin Klein, an envious Jason Dundas, 32, reckons he can fare better. The Entertainment Tonight presenter Jason took to Facebook on Friday to challenge the underwear model to an "abs-off," stripping off to show doubters exactly what he"s made of. The Los Angeles-based stars are both addicted to flaunting and sculpting their torsos in the gym. Jason, who has modelled CK pants as the face of David Jones, laid down the gauntlet to Bieber: "Yo justinbieber Let"s hit the gym tomorrow! It"s an ab off!" The contrasting images of the pair solicited a flurry of comments from fans, many of whom wrote they preferred his physique, with one adding: "At least you don"t have to be shopped." It was revealed on Tuesday that Canadian-born Bieber is the new face of the Calvin Klein campaign, which he fronts with 31-year-old Dutch model, Lara Stone. The Believe star strikes a series of steamy poses in a commercial which sees him pulling in Lara for what appears to be a kiss. MailOnline was the first to exclusively reveal in July Justin had shot an ad for the designer brand.
