This is a diachronic survey of the slang and argot neologisms in the Persian language, specifically those coined in the last few decades and their value as a language teaching and assessment tool. Utilizing slang in the foreign language classroom is a well-established practice on which there has been a universal focus and mainly restricted to the domain of oral language. In the Persian language, slangs have rarely been accepted into the language classroom, and argot has been entirely shunned. Native speakers deal with and process argot and slang terms on a daily basis, as such advanced students of the Persian language need to be aware of and have a basic working understanding of them. Argot and slang are untapped and effective sources in instruction and assessment. To date, no study has been undertaken on the value of these terms in Persian language instruction or how they can best be incorporated into language lessons and proficiency level tests. This paper draws attention to this phenomenon.