buy stockholm stickers, their antwerp stickers aren't nice
you can go to the Kings garden, see the round tower, and when you are there you are near massive street "Strøget" which is worth going a stroll up and down. At the end of the street is Copenhagen's town square "Rådhuspladsen". That should occupy you for half a day easily :)
Find some girls who will do something with you for money.
i would say go look at some of the more famous structures in copenhagen or just walk around the city and enjoy yourself
Man if you like food, go to "Refshaleøen" on a sunny day. There is a street food market out there i just love to death, food from all corners of the world.