I never thought I'd make a good Ninja or anything, but sometimes when I lived in a home I'd be outside the bathroom waiting to get in while a staff was using it, and when they came out they'd jump because I'd be standing there so quietly. Since "Mother Nature" is one thing that can't be rushed, pounding on the door and ordering them to hurry up won't help.
Most of the time though most people don't even seem to notice me at all, even when I'm screaming out a question that no one answered because my asking quietly and calmly was like speaking to the air. And even then they don't answer. Then I might try to say something they *would* notice, like "I'm going to set this building on fire!"
Sometimes it's other people who startle me, because I'm so busy concentrating on something, like reading a book. Reading is the one thing that I do where I just tune the whole world out.
When I was younger I thought I stood out quite a bit due to my somewhat unusual attire. Not many other women wore a jean jacket with a large, hand-painted Troll Doll on the back unless they wanted to look like Mimi from The Drew Carey show.