In smarter countries, people wear masks whenever they are sick as a thoughtful courtesy to protect those around them. I'd like to see that attitude worldwide.
I know you're being cheeky here, but just to be serious for a moment: there's a HUGE literature on the subject of condom use and public-health messaging from the 80s and the HIV crisis. Condoms are...not exactly popular, of course (the TL;DR is that shaming doesn't work very well. Honesty and education >> scolding and shaming when it comes to behavioral change that is intimate and unpleasant).
It's continually astounding to me how many lessons from that pandemic seem to have been forgotten.