There are many different ways taught in self-defense classes, at least the ones my daughters and I took. The first defense recommended was one's voice, in a VERY LOUD manner, as loud as possible. Preferably before an attack even gets near to you. While other body parts were mentioned, I do remember kicking in the privates as one of them.

Years ago when I wrote an op/ed column, I did a lot of research on this and that's where the can of spray paint came up.