Happy Mask Side Quest
After Link has finished trading the Skull Mask, he can borrow the third mask in the Happy Mask Shop, the Spooky Mask. Link can bring it to the boy who walks around imitating Dampé the Gravekeeper all day in the Kakariko Village Graveyard. When Link puts on the mask and speaks to him, he will be frightened and think that it is Dampé the Gravekeeper, but he eventually realizes that it is only a mask. He asks if Link can give it to him, and when Link does so, he purchases it for full price (30 Rupees), without even minding it at all.
Game Icon from Ocarina of Time 3D