The combination of the names of the leader-Jung Yunho and the lead singer-Kim Jaejoong of the Korean/Japanese band TVXQ. It is a couple name used to refer to the relationship between the two boys- as regards to the nature of this as a part of 'fanservice' and friendship or something greater like yaoi has been a topic of constant debate. Since neither have confirmed or denied existence of anything other than friendship but continuing to behave which can be interpreted either way.
Fan 1: I really like YunJae
Fan 2 : They are not real!!
Fan 1:Duh! They are, you must be blind not to see the way they act towards each other...
Fan 2: No way they are just good friends.
Fan 1: You are just too blind to seethe obvious!