Well... if you say "coughing up stuff" then people will probably fill in "potentially icky" but there can also be a step where one is coughing and getting *something*, and that sometimes comes before coughing and getting something that comes in Zombie Apocalypse flavor.

If you tell them you're Really Sick, they'll probably let you cancel, even late. They mostly want to avoid "just didn't feel like showing up to get needles stuck in me".

(