A Koreaboo is a person who indulges in the global phenomenon known as Hallyu or the Korean wave. The Korean wave refers to the significantly increased popularity of South Korean culture around the world since the 21st century, especially among those in Generation Y/the Net Generation.
The largest contributor to Hallyu is the Korean entertainment industry with the rapid growth of Korean dramas, movies, and popular music since the start of the 21st century.
Hey, isn't that BoA Kwon? She turned me into a koreaboo!