Answer:
My first half is normally made of stone, my second is crazy, and I taste sweet when complete.
I'm sometimes white and always wrong. I can break a heart and hurt the strong. I can build love or tear it down. I can make a smile or bring a frown.
It's been around for millions of years, but is never more than a month old. What is it?
I can run but not walk. Wherever I go, thought follows close behind.
You seek it out, when your hunger is ripe. It sits on four legs, and smokes a pipe.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?