Although there is a medical condition where the slightest vibration stimulates them sexually...I don't think this is what you experienced. I think most of us get this funny feeling when we suddenly feel a drop or on a scary amusement ride. I get the same weird feeling if I'm up high and look over the edge. Its hard to explain. In addition when the body perceives danger or a drop, the body reacts with Endorphins and adrenalin. Even babies will act startled if you pretend to bring them down suddenly. This is why amusement parks are so popular - its stimulating. Since you can't stand these kind of rides, you fit the profile of someone who might be sensitive.

I used to have one of those toy View Finders, where you put in a circle of slides pics. One was Niagara Falls and every time I looked, it would give me this weird "fear of falling" sensation. This link explains some of the feeling:

Why do the backs of my legs tingle when I'm afraid? - fear contraction scared | Ask MetaFilter

Here's another link that speaks about the physics and why are bodies/brain react to perceived drops or actual drops/danger. Click the arrow on the diagram:

http://www.washingtonpost.com/wp-srv...eam/index.html