I had the unfortunate experience that shortly after getting my job, I kept getting sick. One thing after the other, I had to miss a lot of work. They were annoyed with me and were rude about me having to call in- even when I brought in a doctor's note for proof. It got to the point that they didn't want me there and were trying to find reasons to fire me or persuade me to quit. Eventually, one evening my manager sent a coworker into the bathroom to spy on me. And I no longer felt safe or comfortable there, resulting in me quitting the next day.