1.
Moon Moon is an internet meme that occurred
April 17th, 2013 on Tumblr. A user posted a picture of a quiz that would tell you what your wolf name was, depending on the
intitials of your first and last name, and his initials were
P.W, in what translated to Moon Moon. He then stated it sounded like a form of mentally retarded gibberish, because well, its Moon Moon. Then after posting his result on tumblr, in a week he had over 100,000 notes to it, in what someone else posted a comic about Moon Moon called "Get The Thing" This went viral on Tumblr and there is a twitter and a Tumblr for
Moon moon.
2. In refrence to 1#, people now use the term "Moon Moon" In the form of that one person that comes along and ruins everything. (Or spoils/
tattles on you) I.E if your friends made plans and secretly
discluded one individual and then someone accidentally told him he wasn't invited. Well, then you would call that person Moon Moon, for telling the discluded one that he could not come and therefore your image looks bad. So, you then throw insults at him/her using the term "Moon Moon"
3. Moon Moon is use to describe someone that is utterly stupid.