maybe they dropped the e?
M VIX (E) N
M VIXEN
Urban Dictionary: Vixen
https:// www.urbandictionary.com/define.php?term=Vixen
A wife or girlfriend in a committed relationship who seeks a male for nsa sex with the permission of and usually in front of her stag husband or boyfriend, without any bi-sexual play or humiliation of her stag.
not sure what the M would be for though.