Shitizen (n.) can refer to those people who are officially citizens but treated unjustly by their government as if they are just indentured servants or even slaves.
When this meaning is used, often it is conveyed with compassion or self-mockery.
They say we are citizens, we know we are shitizens.
In our great Celestial Empire, if you are born to be a shitizen, you will be a shitizen here forever. Go abroad, my friend, only the dumbs remain.
When a toilet is so disgusting and covered with piss/ shit you have to hover over the seat to take care of business. Typically performed in public restrooms.
Dude 1: Yo dude, I was taking the browns to the Super Bowl in a Walmart bathroom the other day, the toilet was so gnarly I had to do an upstanding shitizen!