Drillinge an Bord (1959)

Eduard, Otto and Heinz are identical triplets. Without knowledge of the others, the youngest of them uses an ad text of one brother and a melody of the other to compose a song for a pop-song contest. When he wins a cruise as the first price, the brothers enter a claim for it. So all of them go on vacation - with only one ticket. Even more confusion arises, when a detective on board sees through their game and suspects them to be a notorious gangster trio.