I've thrown up at an amusement park one time, but it wasn't from the rides. I had gone to the beach the day before and burned my legs from my knees all the way to my feet. Badly. It was about 105 degrees and the lines were long and miserable. All the standing and pain and heat got to me and I threw up while I was in line for The Joker's Revenge at Six Flags Magic Mountain.
Oh, and another time my family ditched me and I waited at the exit for them for 5 hours. I didn't throw up then though, just cried.