i would have to say demon drop or any type of intamin freefall because they are pretty old and look like a big scrap of metal just sitting there and knowing the possibility of the brakes failing. another one i would have to say is the end of thunderbolt at kennywood, thats not a OMG!!!! type of scared but a few years ago the operator forgot to put on the brakes and one train hit the back of another going kinda fast, so i always think thats gonna happen to me.