Mark Liberman, a linguist at the University of Pennsylvania, noted recently on the Language Log blog that English does not allow you to pair any old adjective with any old noun in a fixed expression. You may wish someone “good morning”, “good afternoon” or “good night”, but not “good weekend”. You can say that phrase if you like, but your neighbour would look at you quizzically if you lob it over the fence on a Friday evening. In other languages it is perfectly conventional.