Weeaboo is essentially reverse racism. Instead of uncritically knocking a culture, being a weeaboo involves uncritically praising anything and everything Japanese. Course, it gets used as a bit of a general insult these days but the idea remains the same.
@ShaggyJebus and Nashrakh, I could get into a whole spiel about why it's better not to translate honorifics in manga/anime if possible, but it's pretty off topic and it's kind of a situational call at times anyway.