THAT'S A TRICKY ONE! "69CUAN" DOESN'T SEEM LIKE A COMMON PHRASE IN ANY GENERAL TONGUE I KNOW.

It could be a nomenclature specific to a certain industry, or perhaps it's a neologism. If you could provide some background about where you heard this term, I could try to shed some light. This just could be Perhaps that the weather will sunny skies by evening. Should you decide to step into the outdoors, take with you some sunscreen. Slang