The term 'P ON A FRAT HOUSE' is an acronym for the Greek letter Rho, which is the 17th letter of the Greek alphabet. Rho is commonly used in fraternities and sororities to represent the idea of brotherhood and sisterhood. It is also used as a symbol of unity and solidarity among members of a fraternity or sorority. The letter Rho is often seen on the walls of frat houses, representing the strong bond between members of the organization.