These two young fish are swimming along, and an older fish swims by and says, "Morning, boys! How's the water?" And the two young fish just kind of look at each

These two young fish are swimming along, and an older fish swims by and says, "Morning, boys! How's the water?" And the two young fish just kind of look at each other, and then keep swimming. And then after a while, one says to the other, "What the hell is water?"