Oh, I know what you're talking about. I call it "putting the fear of fat" into them. They see you knocking on their back door and they panic.
I had one guy on a mountain bike sprint his little heart out to get around me. That's fine. I'm doing my thing. He gets about 50 yards ahead and stops peddling for a bit. Keeps looking back. Peddles some more. I keep doing my thing. This went on for about 3 miles. I stayed about 50 yards back. I finally wore him out. He pulled over at the next bench (rail trail).
John