system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it a reaction to "shake off" our hands after we slam or jam our fingers?
gpt
One: Distraction - adding stimuli and movement helps to reduce the feeling of pain.

Two: Protection - the cause of the pain isn't exactly understood by your brain, so it starts an immediate reaction to deal with it. Some painful stimuli (hot liquids, acids, biting insects) can be flung away.

Three: Adrenaline - pain stimulates adrenaline, which gets your body wanting to move. 

Four: Blood flow - Injuries can cause blood to pool, shaking your hands will help with blood flow and stop some of the pooling which can cause secondary damage.