From The Apple Wiki

Poo is an Apple Internal application that has so far only been found in Monarch 13A165's RootFS.

It seems to be an extension to EarthBound, as it has the bundle identifier of com.apple.osdiags.Poo.xpc (even through it is a .app)

It also contains a service plist, which logs its errors to /private/var/logs/Earthbound/Poo.txt.

In it's Info.plist, it contains a IP which seems to be a Automatic Private IP address, which is an IP address you see when it's not connected to the internet.

Contents of This App

Entitlements.plist		Info.plist
PkgInfo				Poo
_CodeSignature			com.apple.osdiags.Poo.plist