system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What actually happens when I get a shiver down my spine?
gpt
It's called the pilomotor reflex and like its name it is a reflex. It is mostly stimulated by being a fearful little bitch but can also be caused by a flood of any emotion.

A good example is when you scare the shit out of a cat, all the fur on it goes big to frighten the predator into thinking it's buff when it doesn't even lift. That's what you're doing but you don't have fur unless you're greek so it's useless.