When I was a child, my parents would sometimes take me to a funfair (amusement park) in a small town called Tramore, in southeast Ireland. It featured a very old, rickety roller coaster, with one tall, alarmingly steep drop. The cars held four people, two in front, two in back. There was no actual harness for your body, just a small metal bar to hold you in place. I went on the roller coaster many times, but one ride in particular stands out. My father and younger brother were sitting together, while I was sitting by myself. The car took off, and as it turned around the bend to begin its first climb, the metal bar holding me in snapped open! And no matter how hard I pushed down on it, it wouldn't stay down! Luckily, at another funfair a few years before, I had heard a carnie telling a customer that gravity holds you in place on a roller coaster, that it was almost impossible to fall out. At the time I thought it would be really cool to test that out -- but I never thought that chance would actually fall my way! Since there was nothing else I could do, I just held on and screamed for dear life as we climbed up... up... up... then shot to earth like a downed rocket! Obviously, since I'm here writing this, the carnie had told the truth -- gravity did hold me in. But it was still the scariest ride of my life. And probably the best because of that!