system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 why very hot water can feel very cold, and vice versa

For example, I'm at a friends house, and I'm gonna take a shower. I don't know how to work his shower, so I twist a knob until water comes out.  When I flick my hand under the water, it might feel like ice, but its actually very hot. Or, I might feel as though I've been scalded, when in reality the water is almost freezing. Why is this?
gpt
We have tons of receptors in our skin, like pain receptors. We also have receptors for cold and receptors for hot.

When you put your hand in scalding hot water, that sends a really strong signal to your hand. It stimulates the hot receptors, but because the signal is so strong, it sometimes also stimulates the cold receptors. 

Both cold and hot signals get sent to your brain, which gets confused for a brief over the contradictory signals before it picks out the right one and you feel your hand burning.