In order to really put this story in context I will describe the roommate in question. He was very quiet and unassuming -- almost shy. His hobbies included listening to death metal (although I never heard a note of it as he always used headphones) and programming on the Amiga (he once showed me an impressive disk scanning utility he had written entirely in ASM). I had known this guy for several months and had never seen him drink anything stronger than Coke.
One evening this roommate, myself and some mutual friends decided to play AD&D. The night began with my roommate coming back from the store with a large bottle of Everclear and another of strawberry daiquiri mix. We all tried a little but none of us were really into drinking -- let alone 190-proof grain alcohol (although I did choke down a heavily diluted cap full of the stuff). Our disinterest left my roommate with nearly the entire bottle to himself.
By the time we found the ruined city my roommate was uncharacteristically enthusiastic and not making a lot of sense. Since the DM didn't have anything prepared in the way of a map my roommate volunteered an old map he drew. He spent some time finding it and insisted that he didn't remember the layout, but when we started playing again he began shouting "LEFT!" a lot. Following his lead our party ended up in the middle of the town they had just left while we laughed uncontrollably.
The DM said "I thought you said you didn't know the layout?" to which he replied "I don't, I just remember that you have to go left a bunch!" If I remember correctly it was about this time that his mood swung. He started talking about jumping out the window (we were on the 8th floor) and the DM encouraged this until I told him to shut the fuck up. Something the others didn't know was that my roommate was clinically depressed (later I found out he was on meds but I was never nosey enough to look at the labels). After about 10 minutes of this my roommate curled up on his bed and told everyone to leave.
I woke up the next morning to find about three shots of Everclear left in the bottle. My roommate slept the entire day, only waking to have a brief conversation which he later didn't remember having. A month or so after this he had a severe nervous breakdown and had to move away.