The merging of the words "Japan" and "Wannabe", Japannabe is a term used to describe (typically) white people who wish they were Japanese. These people usually have next to no knowledge of Japanese history, over-use the words "baka" and "kawaii", and even go so far as to claim they are Japanese.
Japannabe: omg u just hate me cuz u bumbed harosheemah lol
Genuine Asian: You do realise that the Tokyo firebombing was a worse offence, right? Please stop posing, gaijin.
Used mostly in online games, reffering a person who has performed or said a stupid or wrong thing. Also used to taunt noobs and newbs.
the word "Baka" in Japaneese simpley means "Stupid".
When you are really really good with something, like the Japs. The word is very often used for people who spend most of their spare time on one specific task and thus becoming very good at that task