Crickets
Pilot fish at a local school takes a couple of days off, and when he returns to work, the resident clownfish is acting odd and smiling a lot. And when the IT director yells at the clownfish to “get that damn thing out of here,” pilot fish is mystified.
But then the clownfish crawls under pilot fish’s desk and retrieves a small electronic device that he says produces a sound like crickets. How did the boss even know it was there? fish wonders. How could he not know, clownfish retorts, with his door open and this thing chirping away nonstop? What clownfish wants to know is how pilot fish could tolerate that noise coming from right under his desk.
Turns out pilot fish had lost his high-frequency hearing a long time ago and could no longer hear crickets, whether real or electronic. Clownfish would have had to find a way to place the chirper about an inch from fish’s ear for the joke to come off.