The Celebrity Juice star appeared with Kelly Brook at the festival to promote their upcoming comedy Keith Lemon: The Film.
Copyright: David Fisher/Rex Features
Lemon began by posing next to a swimming pool with Brook wearing a beige suit and tailored shorts. However, he soon stripped off to a pink T-shirt and leopard print briefs, before baring his bum.
He then removed his T-shirt and posed in the pool while Brook - wearing a tight white dress and red heels - looked on.
Brook appears in Keith Lemon: The Film along with stars including David Hasselhoff, Gary Barlow, Tinchy Stryder, Jedward and Fearne Cotton.
Keith Lemon: The Film is released this August.