Q: Why does Norway have barcodes on their battleships?

Q: Why does Norway have barcodes on their battleships?
A: So when they get back to port, they can Scandinavian.

This is a pun. The critical element of this pun is the word Scandinavian. The country Norway a Scandinavian country, so they could reasonably return home and [be] Scandanavian, but the word Scandinavian also sounds like "Scan the Navy in", and if you had barcodes on your ships, you could scan the barcodes on the ships in order to record whether the ships all came back.