What is up with "Cali?"

I hate when people call California "Cali." I think it is so dumb! It seems to be a highschool term to say. All these highschool kids say that they are going on vacation to "Cali." Or they say "Cali is so fun." I don't get it! California is just as easy to say as "Cali" and it doesn't sound so dumb and immature either. I just think that those cutsey little names people give everything are way stupid. Arrrrrrrrgggggggggggghhhhhhhhhhh!!!!!!!!!!!!!!