Answer:
I am always hungry, I must always be fed. The finger I lick will soon turn red.
Two brothers we are, great burdens we bear. All day we are bitterly pressed. Yet this I will say, we are full all the day, and empty when go to rest.
What kinds of men are always above board?
When liquid splashes me, none seeps through. When I am moved a lot, liquid I spew. When I am hit, color I change. And color, I come in quite a range. What I cover is very complex, and I am very easy to flex.
Has feathers but can't fly. Rests on legs but can't walk.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.