Answer:
I am a desire to munch
What goes up a chimney down but can't go down a chimney up?
I flow from the Homerβs mouth when he sees doughnuts.
I am carried by mad animals.
When young, I am sweet in the sun. When middle-aged, I make you gay. When old, I am valued more than ever. What am I?
No matter how little or how much you use me, you change me every month.