The Boogeyman's Hood is given to you by Eulogy Jones as a rewards for providing aid in persuading Bumble to leave Little Lamplight. As she leaves, a slaver places a collar around her neck, kidnapping her. After you return to Eulogy Jones, you receive the Boogeyman's Hood.
It is argueably the best head-gear for those without access to Power Armor. It cannot be repaired by the Raider Wastehound Helmet, despite looking identical to it. Instead, it must be repaired by NPC's.