I'm starting to get sick of not being able to control my smiling even when I am not happy.

if someone where to say something immature like do-do head, i would lugh and smile uncontrolably. when i talk to other people and they have an odd look on their face i luagh when i dont want to.

People who notice this like to play a "game" with me, called dont smile. Even tho I get thoughts of hurting the person I smile uncontrolably.

What can I do to gain control of this automatic reflex. I only want to smile when I am happy and not in stress situations. I am tired of feeling powerless even over my own body. When I smile uncontrolably I cant get people to under stand that I dont want to joke around and that Im not in the mood.