装B comes from Chinese Netizens. China has developed a deep and constantly evolving language online. It is fascinating to study how Chinese netizens use emoticons in a distinctly different way to westerners and the language constantly morphs in a way that leaves Chinese expatriates baffled even after a short time outside the country. zhuāng bì (pronounce the zh as a short j) is a case in point. It means poser.
Christine Xu gives an in-depth explanation of how 装B came about, given that western characters aren’t generally used by Chinese.