Pigs

Rabbi Dude says:

In order to be kashér, a mammal must possess two features: it must have fully split hooves and it must chew its cud. Nearly every animal has neither of these characteristics; ten have both. There are four animals that have only one, and three of them are ruminants without split hooves.
The fourth, the only animal on the planet with split hooves which does not chew its cud, is the pig. Given that it shows the exterior sign of kashrut but not the interior, the pig is the very symbol of deceit. Not only that, but a pig sleeps with its forelegs extended in front of it, as if to show off to the entire world, "Look at me! I'm kashér!"

How many people there are in the world today who extend their split hooves for all to see, all the while trying to hide the fact that they do not chew their cud....