Sleeper

Someone who you assume is just a normal guy because you only see him in hoodies and baggy jeans. Only to find out later when its summer that hes actually jacked as hell.

Friend1: Yo you know Jake?
Friend2: Yeah what about him?

Friend: Bro look at him on the beach.
Friend2: What the hell? Since when was he that jacked?!

Friend: He's a sleeper bro