A citizen or political figure who is a do-nothing, one who sits like a lame duck and does not participate in the contributing actions of normal society. An extremely boring citizen. A citizen who should be confined to a chair, perhaps even an electric one.
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.