Okay kiddo, you know how when you go pee, it feels pretty good, right? Well, imagine that right after you're done peeing, your body kind of freaks out for a few seconds. This is called post-micturition convulsion syndrome, or PMCS for short.
Basically, PMCS is when your body has a weird reaction after you pee. It can happen to grown-ups too, not just kids! Some people might make some weird noises, get goosebumps, or shiver. But don't worry, it's not dangerous and it doesn't hurt.
Scientists aren't exactly sure why PMCS happens, but they think it might have to do with some nerves in your body getting kind of confused. Your bladder (where your pee comes from) is connected to some nerves that tell your brain when it's full and when it's time to go pee. When you start to pee, these nerves start sending a signal to your brain that makes you feel good. But when you're done peeing, sometimes these nerves keep sending signals even though there's nothing left to pee out. That's what causes the weird sensation.
Again, PMCS is totally normal and nothing to worry about. It's just one of those quirky things that our bodies sometimes do!