Cow King's Hide is a leather chest armor piece that not only offers decent armor and +10 stamina but also +10 of all resistances, making this a nice item for leather wearers.
This item is a World Drop.
Cow King's Hide is an in-game humorous reference to Diablo II. This chestpiece drops from the Cow King in Diablo II's secret cow level. The item stats can be found here.