I'm just naturally creepy. Don't have to do anything.
For example, several months ago I was walking down the block and there was this woman standing by a car, never seen her before in my life. She senses someone approaching and looks up smiling, and the moment she saw my face her smile froze into a creeped out look. I wasn't doing anything unusual, just minding my own business on my morning walk.
If they were going 5mph that'd be fine, but it's usually 1-3mph. It drives my wife nuts in our Volt. A lot of people are oblivious and self-centered. They got there in a car, they'll leave in a car, but in between they don't consider that there are cars moving around all the time, and so they should look out for cars and reversing lights, drivers and cars moving around the lot.