I think it was two things:

1) My father had a hangover from a concert. He drove me to school on the last day of first grade, and had to pull over to v*. My mother always joked that "when your father gets sick, the whole house practically shakes!" It is NOT quiet when he does that, so it scared the heck out of me (still would at 27 years old).

2) Swallowing liquid flouride at a dentist appointment (also age 6) and getting sick in the bathroom sink while panicking to my mother. I remember repeating, "please don't let this happen."

I have had emetophobia since then, but I didn't know there was a name for it. When I discovered this site, I almost cried from happiness that there were others like me.