I'm going to skip my shift at work
Why would you skip your shift? Did something come up?
I don't want to work today
If you have a legitimate reason, it's okay to skip a shift every once in a while.  If you simply don't want to work, you should probably quit your job and find one that you enjoy, no one is forcing you to work there.
I don't want to quit, but I want to show that my job is horrible.
Laying out won't show that your job is horrible. If you are going to have a job you should be giving it your all, then maybe if you find a new opportunity your boss will be able to give you a good review if they call to check references.