Pint-Sized Slasher mask

The Pint-Sized Slasher Gear is an item set in Fallout 3, consisting of the Slasher Knife and the Pint-Sized Slasher Mask. Found in the Tranquility Lane simulation, they are the signature items of the Pint-Sized Slasher, a pre-war serial killer who was believed by some not to be more than a myth.

The mask has a damage resistance of 6 and cannot be repaired (except by merchants), whereas the high-damage knife can be repaired with Knifes, Ant's Sting or other copies of itself (if there were any).

Obtaining
The gear is obtained during the Tranquility Lane quest if you decide to help Betty kill all the residents of Tranquility Lane. It is then located in the doghouse beside the "Abandoned House" and the items are automatically equipped when you receive them.

At the end of the quest or upon exiting the simulation, both mask and knife are automatically removed from your inventory. The glitch which allows you to take items out of the Anchorage Reclamation simulation does not work here due to the fact that that the items are "quest items" and cannot be removed from the player.

The Pint-Sized Slasher Mask appears in the new DLC Point Lookout as an obtainable item located in the Herzog Mine in Kenny's home area and also in room 1K of the Homestead Motel,

Trivia

 * It is likely that this costume is a reference to the horror film Halloween, where, in the opening sequence a young Michael Myers (dressed in a clown halloween costume and armed with a kitchen knife) stabs his older sister to death while she is in her bedroom naked showing her ass and tits.