It's a pain perceiver where capsaicin activates it.

Our senses run on chemicals, and that means sometimes chemicals activate these senses. Capsaicin is similar to a different chemical that our bodies use as signal, and binds to the receptor instead.

You could imagine it like a vending machine that's supposed to dispense soda if you put Euro coins in, but it'll equally dispense soda if you put other flat pieces of metal in it.

... bruh...

to keep us from doing stupid things with our butts.