Brain Freeze

Everyone has all had at least one brain freeze, which is medically referred to as a "cold-stimulus headache." It often lasts a short time, is innocuous, and frequently happens just after you consume a very chilly food. However, if you study its biological or evolutionary origins, it becomes totally nonsensical as to why it occurs. Even though it feels very painful and real for that brief period, no one is aware of what takes place inside the brain during a brain freeze.

According to one explanation, it's because consuming something cold causes a sudden increase in blood flow to the brain. The brain interprets the pressure created by the increased blood flow as a form of pain, which results in what is known as a brain freeze. While that may provide an explanation of the mechanism, it does not address the question of why pain—and not any other emotion—is the perception that the brain makes of the event.