What's the State of Your State?
National State Day is one of the more abstract special days during the year. There's really no concrete way to celebrate it that I know of. Maybe you'll come up with something better.
Those who live in a country like the United States; that is, a country made up of states, can celebrate by rejoicing in the fact that they live in a state. Whether or not it's currently your favorite state doesn't matter.
If you plan to move to another state soon (and it's to a state that you prefer over your current state), you could celebrate that you'll soon be in a better state.
If your body is in a solid state, you can party over that. Just don't party so long that you turn into a liquid state.
Related to that, you could celebrate the various states of matter that the matters around you are in - solid, liquid, gas, plasma.
Finally, you can consider the mental state of your own head and of those around you. Try to improve these states as best you can.
There are probably a few more states I could state, but this is enough for one day.