In my experience, the term "Cali" is more often used by people who aren't actually from California. Many natives I've spoken to tend to call their state by its full name, California, and some even express a slight annoyance at the abbreviation. It seems to be more of a Hollywood or pop culture term, often used in music or television. So, in short, while there may be some Californians who use "Cali," it's not as common as outsiders might think. It's always best to stick with California when referring to the Golden State.