What Does “P.U.” (As in Something Smelly) Stand For? Mark C. asks: What does the letters in the stinky term P.U. stand for? Often used to accuse someone of exceeding his allotted level of funk, P.U. is, surprisingly, not an acronym, but, rather, likely was derived simply from the pronunciation of its parent word. Dating back to the early 17th century, a common exclamation of contempt for a foul odor was pyoo.