For those of you who don't know.
A weeaboo by the original definition when it first arose in the early 2000's meant that if you've ever, EVER done anything, or seen something that originated from Japan, that made you a weeaboo. If you glanced at an episode of Pokémon when you were 6, you were a weeaboo.
But the term evolved, and then became a term for Japanese, or Otaku culture noobs. People who were interested in Japanese culture and media, but were really nooby in that field.
This also split down a separate path to mean two things. Either the aforementioned Otaku noob, or anybody that tried to BE Japanese. This was merely a 'high school' phenomenon though.
ALL cosplayers are weeaboo's by default, yet Japanese people aren't weeaboo's.
I dunno, it's a clique phrase that doesn't really get tossed round anymore, it's the first time I've heard of it for years.