Backpack Keg

This is a keg full of any alcoholic mixture according to the users preference. Every drink of the alcohol the character will roll a D20. On a 1 the character will take no affect from the drink, on a 20 the character will get -5 on dexterity rolls and +5 on charisma rolls. The number changes every 4 up on the roll. 4= +/-1 8=+/-2 12=+/-3 16=+/-4 and 18=+/-4.