system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do I have a problem peeing in public restrooms when other people are around?

I've heard the term "shy bladder" used before but it seems to be more of a mental thing.
gpt
Short answer is that your nervous system has two sub levels. One that kicks in when we're feeling safe and relaxed and promotes digestion, urination, sexual arousal etc etc, things we'd like to do when we feel safe. The other one kicks in when we're not feeling very safe and is responsible for the flight-or-flight response you might heard of. Taking a piss when you're in some kind of danger isn't a very good idea. And while you might not be in any danger in a public restroom your body isn't smart enough to understand that and will just know that you do not feel comfortable in this place and is getting ready to escape if needed.