Roller coasters are by definition scary, but some are absolutely terrifying. Hurtling along at more than 70-80 miles per hour, while hanging upside down, certainly qualifies as absolutely petrifying. Bizarre loops, tummy-turning drops and wicked-fast speeds; these are just a few of the thrilling features that characterize sthese rides. Are you ready for a wild ride? These extreme theme park attractions are some of the fastest, tallest, steepest and, yes, most frightening roller coasters in the country.