That joke may not be funny to you, but it’s hilarious to the tongue-eating isopod. You see, in the Gulf of California there actually exists a critter, Cymothoa exigua, that targets a fish by infiltrating its gills and latching onto its tongue. It proceeds to not only consume the organ, but will then replace it with its own body, providing the fish with a new fully functioning tongue it uses (probably a bit begrudgingly) to grind food against tiny teeth on the roof of its mouth.