If your hand hurts, simply cross your arms to confuse your brain and reduce the perceived pain intensity.
Researchers believe this happens because of conflicting information between two of the brain’s maps: the one for your body and the one for external space.
Since the left hand typically performs actions on the left side of space (and the right hand performs on the right side), these two maps work together to create powerful impulses in response to stimuli. When the arms are crossed, however, the two maps are mismatched and information processing becomes weaker — resulting in less pain.
It's Interesting 