Is a portmanteau of the words "Wannabe" and "Japanese"
Specifically a White American
Anime, or Japanese culture fan, though the definition has been expanded in recent years to include anyone of Western culture(no matter the race) who get hard ons for Japanese culture.
Weeaboos often want to be Japanese and hate Western culture in favor of Japanese, which often most have never even really experience irl, just from
Anime. It's more of a phenomenon in gen
y due to the fact that they came up in the
anime boom, kick started primarily by Toonami, and hyper Japanese gaming of the mid 90s with Playstation.
They are often Anime addicted, and spend tons of money(or their parents money) on
anime merchandise, including cosplay, whole DVD boxsets(imported a lot of the times) plushes, and and bad
anime video games. They are often pretentious about it(the hardcore ones at least) and think that American animation is
crap, not mature, or only uses "crude" art, ignoring the fact that there is nothing mature or realistic about most
anime.
Most of the guy weeaboos think they're some kind of romantics, often swooning over
anime girls and having no grip on reality because they think
anime love is real, and coin themselves as "nice guys" that can't get girls because they're often on the friend line.
Ezra: Hey Steve, do you want to join anime club?
Steve: Nah man, it's full of
pretentious weeaboos who look down on you if you like dubbed
anime.