Medieval Dynasty

This achievement can be unlocked at anytime in the game, but there is an easy opportunity to do so right at the beginning of the game.

Head into Gostovia and talk to the Tavernkeep, Dobroniega. She'll give you 6 Oat Ales to take to Uniegost as part of a quest. Save your game, then talk to her again and ask to see her wares. Sell everything in your inventory except for the Oat Ales so that you can afford to buy a 7th Oat Ale. Once you have 7 (or 6 Ales + any other alcoholic drink), enter your inventory and drink them all by either double-clicking on them, or selecting them and pressing 'F'.

After drinking them all, you'll be at 100% intoxication and the achievement will unlock. Simply reload your save and continue on.