SLPT: Before taking what you think is the biggest shit of your life in the restroom of someone you barely know, make yourself a favor and flush the toilet once to make sure it is functional.
It's a good tip, but shitty.
This just happened to me in the guest bathroom of someone I barely knew. The bathroom was meters away from the meeting.
So let's say I need to take a monster dump, and I test the toilet as you suggest, and I discover that it is not functional. Assuming it is the only toilet within reasonable distance, now what?