system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Brainfreeze

Whenever I get brainfreeze, I was always taught to put your thumb on the roof of your mouth. Is there any actual "science" behind this? Is it really a tiny transfer of body heat that makes the brainfreeze go away, or is your brain just distracted by something so obsurd that it "forgets" about the brainfreeze?
gpt
There is some evidence for it, but pressing your tongue flat against the roof of your mouth works better. 

Brainfreeze happens when your body goes OH SHIT THATS TOO MUCH COLD RIGHT NEXT TO MY BRAIN! So it opens up all the blood vessels trying to warm it up, and that's what caused the pain. Warming it up will shrink the blood vessels back down, no more pain.