Informal and Formal

I would have to say I speak two types of Englishes. When I am around my friends and family I tend to not be so formal.  However, when I am at school my English is more proper. I view school as my job, so I want to use the appropriate English since I am around all kinds of educated teachers and students. It is really shocking, because my two different types of  English turn on and off like a light switch and I do not even realize it.