1) When you're running in a park and an unleashed dog (or two) runs up to you and forces you to slow down/stop. (Usually this is accompanied by the dog owner yelling "Rocky! Bad girl!" or whatever the dog's name is).
2) When you're on the starting line of a race that's late to start, and your GPS watch insists on going into power save mode.
3) When someone driving a car that's a good 200 yards away sees you and unnecessarily goes out of his or her way to stop, slow down, or find another way to completely hold up traffic. Often accompanied by a wave, an eye roll, and/or the mouthing of the words "go ahead".
4) When a guy driving a motorcycle or fast car sees you running and speeds up as a way to defend his masculinity.
5) When families walk in 4-deep horizontal rows on a park path or trail.