Answer:
I am the kind of ant that's good at math.
When it comes to me you go on red and stop on green.
I am the noise Santa's reindeers make
I'm the source of all emotion but I'm caged in a white prison.
My voice is tender my waist is slender and I'm often invited to play. Yet wherever I go I must take my bow or else I have nothing to say.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.