Derived from the word spiffy, spriffy has two meanings. The first meaning what you call a person when they don't act the way you thought they would. For example, a quiet individual might seem normal until you begin speaking too them or a person who seems to have alot of facial expressions ends up having a monotone voice. The second meaning is being a wholly cool person, in the how smart they are, the way they talk, and the way they dress. For example, a nerd who dresses fashionably and talks "cool" is spriffy.
I would never think Justin would sound so monotone when I first met him, that guy's so spriffy
Anthony's so spriffy
, he dresses amazing and knows what he's talking about too!