It was covered in second year French when I studied it in India through Alliance Française.

As a native French speaker from Quebec, I can tell you it's much more common in France, so if you went to school in North America that might explain it.

On a similar vibe, in Catalan oi is used instead of sí in questions, like in "T'has menjat el desdejuni, oi?", which may surely come from oui or the ancient oil in French.