...moldering, eldritch veils of such manifold depravity, the human eye will not process the sheer enormity of their malevolence, and out of self-preservation will merely show you paper bags with faces on them. These faces are still moderately scary, though, so brace yourselves for mild terror! [sound of bat wings]
— Valve, on the hats' true forms
The Mildly Disturbing Halloween Mask is an unlockable headwear item wearable by all classes. It is a brown paper bag with a team-colored face painted on it, with each class having a different "face".
It can be unlocked during the annual Haunted Halloween Special Event by any player who completes the Candy Coroner Scarechievement, which involves collecting 20 player-dropped Halloween pumpkins on Harvest, Mann Manor, Eyeaduct, and Ghost Fort.
This item can only be worn around Halloween or during a Full Moon; at other times of the year, it does not appear in gameplay, unless the server has Halloween mode enabled. However, it can be equipped at any time and can still be viewed on the loadout screen even when it is not visible during games.
October 29, 2009 Patch (Haunted Halloween Special)
- Added this item to the game
September 30, 2010 Patch (Mann-Conomy Update)
- [Undocumented] Added a community-contributed description for this hat.
October 8, 2010 Patch
- This item is now nameable.
October 28, 2010 Patch
- Fixed the Candy Coroner achievement not awarding the Mildly Disturbing Halloween Mask
October 27, 2011 Patch (Scream Fortress Very Scary Halloween Special)
- [Undocumented] The Mildly Disturbing Halloween Mask can now be equipped during the Full Moon.