Someone who is a barrel full of grumpiness. Despite all actions to turn the tidal mood, this mammal refuses efforts on all fronts. Applying the phrase "crank tank" when referring to said offender will often remedy the situation, assisting the grump bucket in performing a 180 degree turnaround.
"He woke up from his nap in full crank tank mode. He was pouting like a grump-asaur!"