The correct spelling of the phrase "SUS PER COEE" is actually "SUSPERIA COEDES," which means "nighttime slaughter" in Latin. The phonetic transcription of the spelling is /sʊsˈpɛriə ˈkoʊdiːz/. The "s" in "susperia" is pronounced as "z" and the "c" in "coedes" is pronounced as a hard "k" sound. This phrase originated from the Roman Empire and was often used to describe violent acts committed in the dark of night.