If you have a lot of body to your hair, or it’s naturally super curly, then it cannot be pin straight. It can be straightened, but not pin straight. I would go to your salon and explain what you want. They could texturize your hair and give you layers to take out some of the body and to calm it down, if you have bigger hair. But, if you have thin hair, then you could use a nice flat iron and straighten your hair to make it pin straight.