I've struggled with a chronic illness for quite some time now, which sometimes requires complicated testing to determine what the hell is going on. Super fun.
Anyway, a few years back and one year into servitude with Hellmart, I went to my specialist and he didn't like my results at all, so I got scheduled for another test. Unfortunately, the tests put you in quarantine for a day or so because of radioactivity.
I told my manager about the test and how many days I would not be able to work (3), trying to get him to understand and take me out of the schedule that hadn't been written yet. He wrote it down, assured me it was fine, etc.
Yeah, I was on that schedule to work by myself for 2/3 days.
I went to the same manager and told him that under no circumstances could I come in - that it wasn't just me being at the hospital all day, but that I had to be away from people.
"But I need you here!" had to have been looping in his head because that's all he bothered to say.
I didn't bother calling out those days and no one said anything about me being missing, but what kind of idiot doesn't understand 'quarantine'? As much fun as it would be to contaminate the crusties, I didn't have it in me to drag my ass there. I'm sure one person would sniffle and I'd be blamed.