Taking snaps in the studio

I avoid as much as possible taking snaps in the studio, only when i am in dire need of it, i go for that. The reason behind it, is i cant stop laughing my heart out while the photographer is clicking. He would first say, sit very straight, don't hunch! Next he would say, move your shoulder back and sit very straight and broad! Now i cant stop giggling about it, Cos to me i feel i am sitting perfectly, but the camera man thinks otherwise!!!. Now when i think, atlast he will click, he will again command, move your shoulders little bit this side or little bit that side. then again, move your head little bit this side again....now i realy cant stop laughing, its really difficult! okay now the photo is going to be taken atlast after so many adjustments, then he would say smile....and i would be controlling myself that i dont burst out laughing on his face. i take a deep breath, smile as much as i can and act all serious at the same time, click click is the only sound u hear next....and i start imagining how the snap is going to come out.....the camera man will request for one more snap and i have to stay still till that moment, click click...................so much for a snap!!