An invisible protective aura that prevents one from feeling any pain whilst shitfaced.
Drink a case then walk into a lamppost to find out for yourself.
Magical plate mail that appears on one's body due to the consumption of the enchanted potion, beer. Beer Armour has an armour class of 15 AND a +6 modifier to your basic charisma characteristic.
Gavin donned the fabled Beer Armour. As he strode through the tavern no man could inflict damage unto his flesh, nor could any woman resist his charm.