Never run down a dark hallway in a house with cats...
Speaking of being startled, when I was a kid my sister had a cat named Max. Max was rather a timid cat, and he didn't much care for me--timid cats never did. Well, in our house we had a long hallway, and one night I was running through it (as kids are wont to do) with the lights turned out. Unbeknownst to me, poor Max was in that hallway. All three bedroom doors were shut, so the only way out was in the direction of the enormously scary human running straight at him at maximum speed. Human eyesight being what it is in the dark, I didn't notice him until I was practically on top of him. Do you know what happened next?
Oh, yes, there was hissing, and growling, and clawing. That much is a given. But the truly remarkable bit is that he jumped. Cats will do that when faced with an imminent attack, but I never knew just how high they can jump in these circumstances. That poor cat propelled himself with Rocket Power off the ground, soared a full ten feet, hit the ceiling--and I don't mean that he brushed it; I mean he would have kept on going if it hadn't been there--and literally bounced off the ceiling. I can still remember hearing the thud. By the time Max was on his way down, I had already closed to zero range, so as he descended he showered me with scratches. It was like he was in three places at once. He hit the ground, ran past me, and fled down the hallway, lightning swift.
Normally I don't appreciate being scratched by cats, but this time I figured right there on the spot that Max had come out of it a lot worse than I had.
Poor thing never trusted me again...