Technically speaking, a "blue moon" is when two full moons appear in one calendar month and (rarely) has anything to do with the actual lunar color. The last blue moon was in July 2015 and will not occur again until January 2018. Hence the phrase: "Once in a blue moon."
Bodily full moons however, are a slightly more common occurrence.
An Alex Hiro mish-mash that ended up on my Patreon.
I was going for the whole future-meets-present thing, but it didn't
seem to go anywhere and sat in my "in the works" desktop folder for
several years. Futa, toys, or just a little nekked grind session? Ehh,
who knows....let your mind wander.