Have you ever had an ice cream headache?
An ice cream headache, or brain freeze, is caused by the rapid cooling of the blood vessels in our sinuses. When we eat something cold the blood vessels constrict. This sends a message to the brain via our trigeminal nerve, which is also the nerve that tells us that our face hurts. That is why we get the painful sensation on our forehead when we eat ice cream.
Possible cures for brain freeze pain (besides avoiding ice cream) include pressing the tongue against the roof of the mouth for 20 seconds, drinking warm water, or breathing in through the mouth and out through the nose to warm the air passages.