My Best Friend's Girl (2008)

When guys get dumped, they hire Tank to take their ex-girlfriends out on the worst date of their lives - an experience so horrible it sends them running gratefully back to their beaus. So when Tank's best friend, Dustin, is dumped by his new girlfriend, Tank naturally offers to help out... and ends up meeting the challenge of a lifetime. Smart, beautiful and headstrong, Alexis is the first girl who knows how to call his bluff, and Tank soon finds himself torn between his loyalty to Dustin and his love for his best friend's girl.

Official website: http://www.mybestfriendsgirlmovie.com/