Grumple Puff

a man or woman who is extremely irritable, winey, and angry with the world for no apparent or valid reason and who attempts to appear happy and fun on the surface but cannot hide their discontent, resulting in a very unpleasant person to be around, a Grumple Puff

"Hey would you like to go hang out with kyle?"
"No way he has been a real Grumple Puff lately."