They call it a common gesture of courtesy to inform people that your home would offer itself to those fleeing some kind of devastation (oppressive regimes, abuse, earthquakes, etc.). However, most people don’t end up in that kind of humanitarian role. What’s the closest you have come?
closest was two Belgian travelers who were SOL and money in Beijing, so I let them crash in an unused classroom for a few days in my school and take showers and wash everything in the staff bathroom and they were real happy.