Smooth Dirt is a huge, completely flat plane of grass with a square-shaped concrete platform in the center. Reaching The Edge™ from the center can take ~30 minutes without the assistance of movement items.
The platform and the grass have editable textures and can be disabled entirely; however, disabling both will cause the owner of the Condo to fall endlessly upon first entry as the condo's items have not loaded in yet.
Smooth Dirt is based on the Garry's Mod map gm_flatgrass; more specifically, the version of the map prior to GMod 13.
Reaching the edge of Smooth Dirt unlocks the achievement "The Edge". It takes 2 minutes to do so from the center by sprinting in an inflatable boat with speed shoes equipped.
It takes significantly longer when just walking or running.
According to Jeff, Smooth Dirt's terrain was smoothened through "natural means," such as bulldozers.
In the top left quadrant of Smooth Dirt, the grass was "folded a thousand times and heat treated to form the ultimate katana zetsubou. The katana jumped on a bus headed for glorious Nippon, and was never seen by human eyes again."
Smooth Dirt's dirt has been blessed by playful meat ghosts who live and thrive in the hidden 25th hour of the night.
Jeff advises owners of Smooth Dirt to "please be considerate of your new neighbors. If you hear voices asking for meat after midnight, do not feed the ground."
On the southwest quadrant of Smooth Dirt, the ground is made entirely out of glossy JPEGs of dirt, printed out individually at a DIY photo lab.
The photos cost millions of dollars in marketing to print.