One of my greatest fears :p I saw someone do that one time actually, and the door that the button opened was really slow moving and irreversible until it had completed opening fully. This was on a train, with all of the passenger seats facing the door in question. The guy that did it had to quickly pull his pants up and then stand there awkwardly while the door finished opening so that he could close it again.
https://www.bbc.com/news/world-asia-38660860
Although it probably takes a few years for all toilets to be replaced...
Is that one that automatically opens the door, or one which automatically starts a full wash of the entire toilet cabinet's interior?
Sometimes the button is red, but it can be any color, sometimes it looks like a flush button.
Another tricky thing is figuring out how to flush the public toilets. The user interface is non standard on every toilet. The most surprising way I've encountered was to step on a button on the floor. (Remember to never press the big green button)