Wikipedia says it's known as brain freeze; shake ache; frigid face; a freezie; frozen-brain syndrome; and a cold-stimulus headache. The Mayo Clinic calls it a "headache attributed to ingestion or inhalation of a cold stimulus."
Most of us just call it an ice-cream headache. And those of us who ride in sub-zero weather know that it can hurt like a sonofabitch.
So far this week, I've ridden my new singlespeed conversion to work twice in morning temperatures in the neighborhood of -15F, give or take a couple of degrees, depending on whose thermometer you believe. In those temps, unless I remember to ride slowly at first, I tend to get about a third of a mile from my house before the front of my head feels like it's being crushed under a Chevy truck. For two or three minutes, I have to roll my head from side to side and blink my eyes while the throbbing pain makes me feel like I'm going to pass out and collapse into a snow bank.
Even if I do ride slowly, I still get a milder ice-cream headache for a minute or two. Once it passes, of course, the rest of the ride is generally enjoyable. But until then ... damn.
It's just one of the costs of riding in winter. And it could be worse, because there are things that hurt a lot more like ... oh, I don't know ... gunshot wounds, burns, gettin' kicked in the 'nads, that kind of stuff.
The staff at Mayo says that headaches caused by cold foods and drinks might be prevented if you "warm up cold foods in the front of your mouth before swallowing." Unfortunately, it's kind of hard to use that method with air when you're pedaling a bike.
I guess we just have to grin and bear it. And remind ourselves that when the temperature rises to 18 again, it's going to feel really, really good.