Read the following context and answer the question.
Context: Alcohol just never seemed to be an intoxicating substance for him . He could drink extensively , the strongest liquor available ( and in fact his chosen beverage was Absinthe ) , but still remain completely sober . Marijuana acted much like an energy drink would to someone else .
Question: Why is their friend able to drink so much ?
Answer:


They are used to the effects of alcohol .