When you always point out comb overs and your friends they have to stop you again from going over to the poor guy and showing him the light of being Sly.
When you are always trying to convince your haired friends to join the Sly side.
When you talk about being Sly more than sports.
When you are driving or in a store and look over at another Sly guy and you give each other 'the look' or maybe a self head rub, no words are said, and you both know you are part of the Sly club.
When you think about your next tattoo and wonder how to get away with getting something related to Sly without too much teasing from people. (I have a few planned)