Sick people who go out - or parents who take their sick kids out - in public and touch door handles and anything else they can find with their disgusting, germy hands. Purell yourselves! It's not that hard. Dime sized amount, rub it in. And unless it's something like school (and even then!) keep your snotty kids at HOME and AWAY from the playground. We don't want your illness. I don't want my son sick.
And then they're all, "Well, everyone gets sick! It's just a fact of life!"
I don't get sick unless you prance around with your germs. My son doesn't get sick unless you take your sick kid to the park and have him or her go snot-nose-first down the slide.