I'm going to sleep on the toilet at work
That feels very dirty. Why do you need to sleep on the toilet?
I don't feel good at work and I can't take a nap in a normal way
It's not good to sleep on the job. You might get fired if you get caught.
I'm going ot pass out before anyone notices
If you are sleep deprived, then you need to tell your boss immediately so that you can be excused and someone can assist you in going home. I'm sure your boss won't mind you missing work one day compared to you potentially missing work for more days because of a health issue that may cause you being sleep deprived from work.