Party Girl Party Boy

Party Boy or Party Girl (depending on the player character's gender) is a perk added to Fallout 3 with the Broken Steel add-on and Fallout 4.

Fallout 3
The player will no longer suffer the withdrawal effects from an alcohol addiction.

Fallout 4

 * Rank 1: There's no chance you'll get addicted to alcohol.
 * Rank 2: Human or humaniod companions can now consume alcohol, and will receive a morale boost which will make them more resilient in battle
 * Rank 3: Residents of your workshop settlements can now consume alcohol, and will recieve a morale boost which will make them more productive.