Goosebumps are caused by an automatic response by your body to cold or emotions like fear or excitement. The scientific name for goosebumps is the pilomotor reflex – and this is the cause of what makes the hairs on your arms stand on end. If you experience something – say a fright – a nerve reaction happens and a message is sent to the muscles that control the hairs on your skin. That makes the muscles contract and this is what causes the hairs to stand up. I guess it’s called ‘goosebumps’ because it looks like the skin of a plucked goose or chicken!