Davy Jones' Gravy
Davy Jones' Gravy is a dark, murky fecal/water combination that is the result of a particularly non-solid bowel movement, obscuring from vision all below it's putrid depths. Commonly found in public restrooms and port-o-potties.
I went to use the outhouse at the construction site, but it was so full that my balls dipped into Davy Jones' Gravy when I sat down.