Currently in the server featuring the 3 H'ween mask rares from October 17th - October 25th and then from Oct 26th-31st you'll get them dropped featuring different two different rares!
You can get these while you're fighting any NPC, fishing, mining, woodcutting, or thieving(pickpocket/stalls). Be watching the ground for a [classified] item drop!
Good luck getting [classifieds] so you can [spoiler] on [spoilers] and share the wealth!