A distinguished colleague (whom I will spare the outing) teaches in the lecture room after me.  I received this email from him:

Subject: Any chance you could erase the Leverdome blackboard?

Or is this a Coase theorem thing?

Not the Coase Theorem, no.  The Coase Theorem is all about parties coming together to form agreeements that enhance welfare.  No, my dust-bound comrade this is much simpler seeing as how aggregate welfare is improved by the unilateral deviation of a single agent, namely me.

You see those days when we were following the conventional norm, according to which each Professor erases the chalkboard after his own lecture leaving a clean board for the next class, we were leaving a free lunch just sitting there on the table.  Because any one of us could have changed course, leaving the board to be erased by the next guy before his class, thus triggering a switch to the superior erase-before convention.

Now as I am sure I don’t have to explain to you,  once the convention is settled every Professor erases exactly once per day.  So nobody is any worse off.  But as you have by now noticed, that one particular Professor who initiated the switch avoids erasing that one time and is therefore strictly better off.  A Pareto improvement! but of course you are now well-trained at spotting those having just yesterday surveyed my lecture notes covering that very subject as you were erasing them from the Leverdome chalkboard.