In the City of Pain mission, while sneaking through the camp, there are a few vomiting soldiers in some of the remote alleys. Once you see a soldier leaning on a wall, he is vomiting. Kill quickly and from afar!!!!
Though relatively sparse, snakes may be encountered anywhere in the wilderness and inside some structures. When the player is near one, it will rattle and hiss. If the player gets too close, the snake will bite causing momentary loss of player control and a blurry and discoloured screen.
Two characters are heavily implied to be using weed. Dead enemies can be looted and sometimes they are carrying paraphernalia. Main character gets drugged in a portion of the story.