I have a couple of times.. Gather round while Elky explains.
I was on a School Holiday to Italy, and one of the days we went to a Theme-park called Gardaland. Well, my being pumped up and ready for some thrills did the best, fastest etc.. Roller Coaster there was there. It was the Blue-tornado (Look it up)
I was sitting beside a complete random person while all my friends waited for me to finish. When I got on, we all got strapped in expect for me.. The staff in charge of this section, (You know, fastening seats and belts etc..) must have forgotten about me. At this point I was getting a wee bit nervous wondering what was going on, and then before I could say anything the Roller Coaster had started.
It was a long journey to the top at about 5 mph.. Whenever we reached the top, I was shitting a brick. We went down the first slope and were coming close to the loop-to-loop and then it happened. My seat lifted up and I pulled it down as hard as I could till I heard a click and closed my eyes.
I just about made it..
Then after that I went on another Roller Coaster and back on to that one again. ^^ Haha.
Then once I chocked on food for about 25 seconds, going red in the face and coughed it back up..
The End.