Used as an adjective crankstastic is used to describe a feeling of Euphoria. Coming from the root words of crank and bombtastic it combines the joy of using crank, a drug, with elements of bombtasticity, greatness.
Girl: Turn up the volume on the radio! That song is cranktastic!
Boyfriend: Whatever keeps you happy baby. *cranks radio up*
Boyfriend's friend: man your girl has a addiction problem with this song.