A Korean slang /
meme for 'Hello'. 'Bo-' is a prefix for Bokyem, a Korean famous youtuber, and '-iru' means Hairu which is an old-fashioned expression to say
hi in South Korea. It was at first just how Bokyem say hi on his intro, but spread through the Internet as Bokyem became famous, and even
people who are not a Bokyem's fan started to use this word.