I'm still wondering about the following phenomenon:
-Góðan daginn!
-Góðan dag!
or
-Góðan dag!
-Góðan daginn!
1. If the first person to speak picks one of the pair, must you pick the other? All the speakers on my tape seem to do so.
2. Obviously, the case involved here is accusative (masc. sing.). Góðan daginn, according to strict rules which I can see may not apply here, is surely incorrect grammar, as the adjective should be weak before a noun + article, so one would expect Góða daginn. Or is there another rule which makes it an exception?