Drinking beer makes Duke tougher and reduces damage by 75% for a short period of time, although when the player consumes a beer Duke becomes drunk and his vision becomes very blurry. There is also a slight slow motion effect, but not enough to really change gameplay, besides humorously making sounds deeper. Beer in DNF is in a large 40 oz. can. Duke can carry beer in his inventory to drink later.
To unlock some trophies/achievements, drink beer for the first time, drink beer and take steroids together, or drink all 8 beers in the strip club.
The small text on the lower portion of the can reads "Some text that is much too small to read, but that gives the impression that there's actually something worthwhile.".