True to form, OmniBrain has posted an informative video about the “ice cream headache” also known as “Iceberger’s syndrome.” This is the nominally painful headache one experiences after eating too much of something extremely cold. While no “silent killer,” as the video jokingly claims, “brain freeze” is actually a real thing (sphenopalatine ganglioneuralgia) with a perfectly reasonable cause.

When you consume something very cold like ice cream or a 40 oz Slushie, it rapidly chills the roof of your mouth (the hard palate). Just above the hard palate is the sphenopalatine nerve which is extremely sensitive to rapid changes in temperature. As the cold food cools the hard palate, it stimulates the sphenopalatine nerve, “tricking” the brain into thinking that you are in an extremely cold environment. And, the body’s reaction to suddenly being in a very cold place is to constrict the blood vessels in the brain, reducing blood flow to the brain. The pain is actually caused by the subsequent influx of warm blood which then forces the vessels open. Since the pain is actually felt in the head, rather than the roof of your mouth, the pain is “referred.”
However, Iceberger’s syndrome has a cure! Just warm the hard palate by placing your tongue on it. This will reduce the stimulation on the nerve behind it and reduce the stricture of the cerebral blood vessels.
(Note: I thought it might also be from cooling the blood traveling to the brain via the vessel sitting close to the throat.