In David Foster Wallace's "This Is Water" Commencement Speech, there is a story used as a metaphor about a fish asking another fish "what the hell is water":
There are these two young fish swimming along and they happen to meet an older fish swimming the other way, who nods at them and says “Morning, boys. How’s the water?” And the two young fish swim on for a bit, and then eventually one of them looks over at the other and goes “What the hell is water?”
I had the impression this story was something I had heard before, and DFW was there only using or slightly modifying a popular joke to illustrate his point. However when now I tried to find its origin everything seems to point to This Is Water.
I am looking for any reference to the story or similar stories before 2005 or the confirmation of this not being a common tale in the American/Anglosaxon culture.