What is Brainfreeze?

"Pain that begins a few seconds after rapid ingestion of cold foods or beverages and peaks in 30-60 seconds. The pain is usually located in the midfrontal area, but can be unilateral in the temporal, frontal, or retro-orbital region. It is a stabbing or aching type of pain that recedes 10-20 seconds after its onset. " from Hulihan, 1997

Brain Freeze, AKA ice cream headache seems to occur when the blood vessels in the roof of the mouth constrict due to the cold, and then dilate quickly. It is an example of referred pain. That is, pain experienced adjacent to or a distance from the actual presumed site of injury. Interestingly (or not), through personal experimentation, Smith (1968) could only induce brain freeze using ice cubes in hot weather and not in cold weather.  

"No treatment is usually required (ed: but occasionally is er what?), and sufferers rarely seek medical attention...avoiding contact with the cold food with this area can effectively eliminate the symptoms. Most people arrive at such preventative measures without the advice of doctors. Ice cream abstinence is not indicated." from Hulihan, 1997