Beautiful thing made me gay. Literally!
Had struggled with my sexuality all my way through my teenage years, making myself think it was a phase, something that I was going through. I didn't think I could possibly be gay because I didn't look like or want to be like the only gay characters you got to see on television and film - people like Julian Clary, or other outrageous gay characters. I didn't like pink, I didn't like feather boas, I didn't want to be a girl, so I just assumed on a fundamental level I wasn't gay.
One evening I caught this film, and it was like a lightbulb switching on in my head. At the end, I remember saying to myself "Oh, I'm gay then". That was it from that point onwards - never looked back, and never once doubted myself or my sexuality.
All it took was a depiction of gay people my age where they were just...people. Who happened to like people of the same sex.
EDIT: Of course, nowadays you see a much larger host of positive gay role models, but for someone my age back in the late 90s there really did seem to be only one way to "be" a gay man according to the national media and if you didn't fit that stereotype you were lost.