Its name is a reference to the Plants vs. Zombies achievement Don't Pea in the Pool, as well as a portmanteau of the rule "don't pee in the pool," a common rule in public pools, and "pea."
Description
When the residents of Sundrop Hills can't get away to Lost Keys Lake, their backyard pools help scratch that "gotta get wet outdoors" itch.
Strategy
One of the closest pools to the spawn point, near the Out of Shape Human
As hinted by the medal's name and description, you need to have a Peashooter stand on a pool. After doing that, the medal should unlock immediately.
A pool near the Out of Shape Human, which is quite close to the spawn point, can be used to unlock this medal.