Ocarina of Time Masks
Keaton Mask: Buy this mask at the Happy Mask Shop for a few rupees. Bring it to the Guard near Death Mountain, and collect a few extra rupees.
Skull Mask: There’s a Skull Kid in the Woods that is alone and afraid others don’t think he is scary enough. Give him this mask and make him happy. However, you just lost more than you bought the mask for.
Spooky Mask: You know that kid in the graveyard? Give him this mask to scare people with. You don’t gain or lose anything for it.
The Bunny Hood: Change the Time of Day to night, and look for the runner somewhere in Hyrule Field (if you played the song at bridge, and changed it to night, then the runner should be around the Gerudo Valley Area, or a little bit closer to Lon Lon ranch there). Make sure you wallet is empty, because he’ll give you a giant rupee, which costs a lot of money!
Mask of Truth: This Mask allows you to talk to Gossip Stones around Hyrule.
Gerudo/Goron/Zora Masks: If you wear these masks, people will give you different responses for each mask.