The term PIN KIN can be broken down into three separate words: PEG, SSN, and USERNAME. PEG is a 3 letter acronym for 'Pole, Elevation, and Ground' which is used in surveying to measure the elevation of a point relative to a reference point. SSN stands for Social Security Number, which is a nine-digit number issued by the United States government to track an individual's income and tax information. Finally, USERNAME is an 8 letter word that refers to a unique identifier used to log into a computer system or other online service.