MooseKnuckle is a giant fupa. Much larger than a standard fupa and generally can be seen because Molly is wearing leggings 3 sizes too small and the moose knuckle kinda blinds you and hurts your eyes. It also probably stinks.
Molly Golightly doesnt just have a big oleflappy fupa that smells like chicken cutlets, she has a giant MooseKnuckle.