Brain freezes always strike at the worst possible time. You're innocently enjoying a cold treat and—wham! A crippling headache ruins the next bite. This video from Mental Floss sheds some light on why we get them. "Ice cream headaches" may exist to regulate our body temperature. Experts speculate they're caused by the constriction and dilation of blood vessels, which occurs when something cold touches the roof of the mouth. Our brains interpret this as pain, and we're defenseless against the ensuing headache. If you want to speed up the healing process, the video suggests drinking some warm water—otherwise you (and your ice cream) will just have to wait it out.