Whenever I want out of work I will give myself horrible diarrhea.
Is there a reason why you want to skip work?
I hate my job and I want a vacation.
If you hate work that much you might want to try and find a new job. You shouldn't be trying to find excuses to get out of work.
I think you are being naive and unreasonable. I'm doing what I want to do and if you disagree with me, I'll just ignore you.
Eventually you're going to be fired, as you can't always get out of work for the same reason. So it would just make more sense to quit and find a new job-- would it not?