Came from someone's first name, but evolved for other uses.
Other forms: Dernariffic, derntastic, derniful, dernaliscious, dernie to the max! (Or you can make up your own)
-"I've got the dernie card!" (referring to the lowest card when playing a card game with cards of varying value... Deuces specifically).
-That's so dernie! (saying something was bad or not as good as expected).
-Dernie to the max!