Rules - Taken from SIDEQUEST Issue 4
A character may drink a number of drinks equal to 2x their constitution modifier before needing to make a constitution save, providing the strength of the beverage is not greater than their constitution score.
Once a character consumes a beverage with a strength greater than their constitution score, or they have consumed a number of beverages equal to 2x their constitution modifier, they must make a constitution save each time they drink an alcoholic beverage.
The DC of the constitution save is equal to the strength of the beverage.
If the character passes their constitution save, they may continue to drink as normal.
If the character fails their constitution save, they gain a level of drunkenness, as indicated in the accompanying table.
If the character fails their constitution save by 10 or more, they gain two levels of drunkenness.
Drunkenness lasts for two hours per level of drunkenness or until the character completes a long rest
If a character reaches level 4 drunkenness, they gain a level of exhaustion after their next long rest.
If a character reaches level 6 drunkenness, they gain two levels of exhaustion after their next long rest.