A pigpen is an enclosed area where pigs are kept, usually with a fence or walls to keep the animals from wandering off. The ground is often muddy because pigs love to roll in wet dirt to cool themselves down, since they can't sweat like people do. While a pigpen might look messy, it's actually the pigs' home where they eat, sleep, and socialize with other pigs.

The word also describes any extremely messy place. If your room has clothes scattered everywhere, books piled on the floor, and candy wrappers on your desk, someone might walk in and say, “This place is a pigpen!” They mean it looks chaotic and dirty, like a muddy pig enclosure. It's not a compliment.

You might also hear about the pigpen cipher, a simple code where letters are replaced with geometric symbols. Kids sometimes use it to write secret messages to friends. The cipher got its name because the grid pattern used to create it looks like the fences of a pigpen.