A famous Japanese school girl group "AKB48"
Japanese school girls have been creating urban  languages continually and sometimes they become a social phenomenon. Today we  would like to introduce you a commonly-used term “KY”. Although it is created by  the Japanese high school girls, it is used everywhere in Japan today across the  generations. If you ask a question to North American people what this term  means, we are sure that most of them would answer “Is it K-Y Jelly?” that is well known  as a sexual lubricant, a product from Johnson and Johnson.
Well the  answer is “incorrect” and it has nothing to do with “K-Y Jelly”. KY’s “K” stands  for “Kuuki” which means “air” and “Y” stands for “Yomenai” which means “cannot  read”. In direct translation, it would become “one cannot read the air.” In  fact, it is used to describe “a person who cannot sense the atmosphere” or “a  person who cannot read between the lines.” It would be used in a sentence such  as “He is such a KY. He always brings up trouble when all of us are having a  great time” “The new Prime Minister Hatoyama should not become KY in foreign  policy. It is not a cut and dry issue.” The unique part is that Roman alphabet  is combined with Japanese. Japanese school girls are so creative that many urban  languages like this are generated frequently.
We would like to introduce  you two other urban languages.
“超SW” 
“超=Super,  S=Seikaku(personality), W=Warui(bad)” that make it “One has a really bad  personality.”
Sentence example: “My boss is  超SW.”
“MG5”
“M=Maji(Really), G=Gire(get mad), 5(5 seconds till)” that  make it “5 seconds till one gets really mad.” 
Sentence example: “That man  was such an KY that I was MG5 and had a very hard time controlling myself.”
