Masticator's ear

The  is the left ear of the Masticator, bitten off in a boxing match in 2241.

When you deliver the knock-out blow to the Masticator during the boxing match, the ear might be added to your inventory.

Similarly, the Masticator can rip your ear off if he hits you while you have 110 HP or less. This must happen in order for the player to be able to bite off the Masticator's ear. (Roughly 160+ unarmed is also necessary).

No actual uses beyond being a trophy of becoming a Prizefighter, vends for $750 at Renesco's Pharmacy or New Reno Arms.

Behind the scenes
This is a reference to the infamous boxing incident when Mike Tyson Bit off a portion of Evander Holyfield's Ear.