Once you receive 10 medals in Four Swords, you can now do the riddle quest in Link to the Past. The riddle quest is a little scavenger hunt type thing. You need to collect 10 items in which the third lumberjack describes. These items are:

1 - A cucco. You can find one right in Kakariko Village.
2 - A crab.
3 - Red rupee.
4 - A fish.
5 - Octoballoon. This thing is a big red ball then it explodes into little pieces. Collect a little piece and you've got one.
6 - Slime.
7 - Squirrel. These are found up by where you found the Master Sword.
8 - Fake Master Sword.
9 - An apple. Run into the trees and you'll eventually find one.
10 - A cukeman. For this one, you need to sprinkle magic powder on the green blob things that walk around aimlessly and electrocute you when you slash them with your sword.

If you give all 10 items to the lumberjack, he'll teach you the Hurricane Spin. The Hurricane Spin is like that awesome spin attack in Wind Waker, but this one can last longer, and you need to control it. Also, you need your bug catching net to catch those items.