This one is interesting...
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13. Thaw your brain!
Too much Chipwich too fast will freeze the brains of lesser men. As for you, press your tongue flat against the roof of your mouth, covering as much as you can. "Since the nerves in the roof of your mouth get extremely cold, your body thinks your brain is freezing, too," says Abo. "In compensating, it overheats, causing an ice-cream headache." The more pressure you apply to the roof of your mouth, the faster your headache will subside.
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This used to happen to me, but I then discovered that if I drank a glass of water before starting to eat the big icecream, my head wouldn't hurt.