Has something ever made your hair stand on end? I explain. This expression is the idiom make someone's hair stand on end which means "to cause someone to be very frightened".
So, now, you already know what this expression really is, probably you'll agree that at least one time in your life, you felt like something made your hair stand on end.
It's not difficult really! Maybe a sci-fi film that you watched very late on telly or a friend or cousin that played a trick on you, made your hair stand on