Liquor has more alcohol levels than beer, if he is drinking it straight from the bottle that indicts he will be consuming lots of alcohol which could lead him to doing dangers things and possibly getting alcohol poising.
More details ? , but there are some basic questions you can ask , like , Are there any GMOs in the food or How is the product made , Is the product made naturally or by man, Hand made or made by machinery.
Tolerance means that after continued drinking, consumption of a constant amount of alcohol produces a lesser effect or increasing amounts of alcohol are necessary to produce the same effect