A Callum is someone who is very smart academically yet lacks general
common sense.
They tend to rarely have any thoughts and when a thought does occasionally come to the front they must announce it
immediately. They often enjoy things such as fishing and talking about themselves in third person. An extreme case of Callumism would cause the person to call some women 'naughty girls.'
Being called a Callum could be thought to be an insult but is often quite an
affectionate term used between friends.