Amulet of Hostility (3.5e Equipment)
From D&D Wiki
This amulet looks just like a plain golden amulet. If worn, it sends a message that all surrounding the wearer are hostile, and become a target to the wearer. Each turn the wearer must make a DC20 Will Save to try to get the amulet off, enough time to sell it to another before it reappears the morning after. If the amulet is destroyed by another creature the amulet shall reform on them.
A successful calm spell or remove curse can get the curse off.