Residook takes many forms. It's frequently seen as a brownish film, butt it can also take a nutty or chunky form which quickly transforms itself to a streak often mistaken for a skid mark. Actual skid marks are caused by a leader piece or turtle tail which has exited the anus but still resides as part of a larger turd. Residook is taken from inside the anus.
Perhaps the most difficult to identify form of residook is when a digit (fingers or toes) is used to explore inside the brown eye. After removal, residook finds a new home under the nail causing many people with residook to be mistaken for an auto mechanic.
This is the term for residual fecal matter stuck on the sides of a toilet bowl after a flush. Alternately, the focal matter remaining on a butt after an incomplete wipe.