The Wedding Ringer.

Doug Harris is a loveable but socially awkward groom-to-be with a problem: he has no best man. With less than two weeks to go until he marries the girl of his dreams, Doug is referred to Jimmy Callahan, owner and CEO of Best Man, Inc., a company that provides flattering best men for socially challenged guys in need. What ensues is a hilarious wedding charade as they try to pull off the big con, and an unexpected budding bromance between Doug and his fake best man Jimmy.