P.O pronounced Pee-oh is a two letter acronym for Polecat odour. It is used to describe the next level up from B.O ( body odour). P.O. is used to describe cases where body odour has been allowed to concentrate to such a pungent state that it instantly triggers the human gag reflex when encountered.
Man, I just tried to help that Jakey up from the pavement and his P.O. nearly made me honk