The Skull Mask is an item in Ocarina of Time. It is a mask that was crafted to look like a monster and to make one look scary as well as tough. It is a part of the Happy Mask Side Quest and is the second accessible mask in the Happy Mask Shop.
Wearing this mask will also keep Keese from attacking Link.
Happy Mask Side Quest
After Link has finished delivering the Keaton Mask, he can borrow the second mask, the Skull Mask. Link can head to the forest in Lost Woods, where as soon he enters it, he can walk to the left to find Skull Kid, who stands on a tree stump playing Saria's Song. When Link talks to him while wearing the Skull Mask, he will become interested in it and asks Link if he can have it. If Link agrees, he will pay 10 Rupees for the 20 Rupee mask, less than what it actually costs.