is a mask in the Hearts of Stone
These can only be received if one loses against the dwarves playing gwent at the wedding reception during Dead Man's Party. Be warned you'll also lose 5% of your money as well for losing.
The ass ears can be equipped to one of Geralt's pockets and thus be worn at any time.
If the player wishes to wear these along with The Professor's spectacles, they can do so by finding the diagram for the Concealment kit.
Associated quest Edit