Answer:
I come in different colors and shapes. Some parts of me are curvy some are straight. You can put me anywhere you like but there is only one right place for me.
I am expelled from you orally with a sound
What gets sharper the more you use it?
I work when I play and play when I work
I plow and plow but never sow.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.