https://www.smithsonianmag.com/science-nature/a-hot-drink-on-a-hot-day-can-cool-you-down-1338875/
It triggers your body to start sweating a lot, so if the humidity is sufficiently low, that sweat evaporates, taking body-heat with it, resulting in a net cooling effect.
Note that this would not work in high-humidity areas, and it’s a bad idea if the individual is already suffering from dehydration or heat shock/stroke.
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