The article mentions the chalkboards having been removed at Cambridge, but I recall one of the colleges having chalkboards in the toilets at one of the sites¹. They were a curious mix of nerdy jokes riffing on regular toilet graffiti, jokes that felt stolen from Futurama, and a few apparent attempts at some actual work. I think the playfulness allowed them to be interesting, as you can place offbeat thoughts on to them without tying yourself to them too deeply.

¹ Can't recall which one it was, but suspect they'd be a casualty of the past year anyway. Edit: Pretty sure it was the INI.