You know how it is: you unwrap a mint, pop it in, and suddenly your mouth is a wintry wonderland of soothing flavor. There's only one word for this: It's cool. But that is, obviously, a totally different sensation than one that you get after your first taste of chili sauce made from Carolina Reaper, reportedly the world's hottest pepper. Then the vibe is less winter wonderland and more "My facehole's on fire!"  So: Why do minty things taste cool and spicy things taste hot, and why do we describe these flavors in terms of temperature?  The short answer is that some chemicals activate the same sensors that our bodies use to detect actual cold and heat. The way we experience, like, pretty much everything is by way of ion channels. These are proteins that line our nerve cells, each triggered by a different thing, like being in the presence of sugar, or exposed to light, or how much CO2 there is in your blood.  When an ion channel is triggered, it opens up and allows a bunch of ions to flow into the nerve cell, changing its electrical charge. This acts like a kind of switch being flipped, and it sends a kind of signal through the nervous system to the brain which interprets this stimulus as a sensation, like sweet or bright or I need more oxygen.  But sometimes, these ion channels can be fooled, especially those in our mouths. Some chemicals can bind with these proteins and cause that whole cascade to occur, even without the actual stimulus taking place. One of these easily fooled proteins is called TRPM8. It's found in the nerve cells in your skin and mouth, and it's triggered by cold temperatures.  Now the active ingredient in mint is the compound menthol, and it happens to bind to TRPM8 perfectly, triggering the ion channel just like a gulp of ice-cold water would.  So when you taste menthol, it convinces your brain that something cold is happening in your mouth, when really you're just sucking on a candy cane. And a similar phenomenon happens with spicy foods. In this case, it's a different ion channel called VR1 that gets the fake weather report; VR1 is usually triggered by heat as well as by compounds that your cells release when they're injured, signalling pain.  But it, too, is easily duped by chemical imposters, especially capsaicin, the oily compound that gives peppers their spicy flavor. When that oil from the peppers binds to your VR1, it signals your brain that your mouth is hot, which makes your ghost-chili taco just taste like burning.  So when we say that foods taste hot or cool, we're not really speaking metaphorically. We're just reporting what our silly brains are telling us.  Thanks for asking, and thanks especially to our Subbable subscribers, who keep these answers coming. If you have a quick question, you can let us know on Facebook, Twitter, Tumblr, or down in the comments below, and don't forget to go to YouTube.com/SciShow and subscribe.