At home, I would guess.
Can't remember when it was or really what I thought of it at the time. I know I've watched it, but I guess I just thought it was weird and funny and essentially forgot about it.
Probably a 1, although 0's a possibility.
Second watch (18th July 2012)Edit
I think because of the imminent release of The Dark Knight Rises Christian Bale was on my radar. I read something about Bale being attracted to the role of Bruce Wayne, seeing him as suffering on some level from an intense mental instability (or at least that's how I interpreted what I read and thought it was interesting). Anyway, that connected with American Psycho and I thought I'd watch it again, since my only memory of it was kind of caricatured.
I definitely enjoyed it, it's intense and surreal, and that's good. I suppose it's not a realistic scenario, which maybe diminishes its significance, but it remains darkly enjoyable to watch.