When you eat ice cream or drink an icy drink too quickly, you can get Brain Freeze, which results in a monstrous head pain. This is because the top of your mouth gets too cold, and a nerve in this area is connected to the front of the brain.
To stop an ice cream headache quickly, just put your thumb inside your mouth (like you are going to suck your thumb), and press on the roof of your mouth - right behind your teeth. The pain will go away immediately. Another method would be to alternate between ice-cold ice cream or smoothie and a sip of hot coffee.