What is the correct plural form of the noun "beer"? It has always bugged me when my friends ask me, "Hey, do you want to drink some beers tonight?"
The plural form of the noun "beer" in the context you have provided is "beers."
The plural form of the noun "beer" in the context of your friends asking you to have some drinks is "beers."
Your friends are discussing certain units of beer that you will drink, whether they are bottles of beer, cans of beer, mugs of beer, or anything else. Therefore, these multiple units of beer are referred to as "beers."
On its own, beer is uncountable. At best, it can be measured by liters and such. But referring to units, such as bottles, cans, or mugs, makes "beers" perfectly valid.