Number five, brain freeze.
You're crushing a milkshake way too fast and suddenly your forehead feels like it's being hit with an ice pick. Most of us laugh off a brain freeze, but for some, that sudden cold shock can trigger the vagus nerve. This nerve controls your heart rate, and an intense chill can cause your heart to skip a beat or go into a dangerous, irregular rhythm called an arrhythmia. It's rare, but your body's ice cream headache is actually your nervous system screaming in panic.