In Bringing Home the Bacon, an adventurer assisted Eli Bacon in raising awareness of the usefulness of pigs. During this task, bacon addicts (crazed by Eli's discovery of the delectable meat) forced Eli to hide his pigs underground in a cellar. After successfully promoting the pigs, people came to Eli to buy breeding pigs, and seeing the pigs underground, figured that was the best way to raise them.
If a player attempts to enter a pig pit on a free-to-play server a message will appear stating "Something interesting happens. However, it is so small and insignificant that overall nothing interesting happens." This is a reference to the common game message "Nothing interesting happens."
The Lumbridge pit was removed with the release of the Battle of Lumbridge. It was later re-added, but has since disappeared.