A hybrid of the words "boo" and "boring."
Used to indicate extreme displeasure at something which was expected to be interesting and exciting.
Person 1: "Hey, check out this article about the Antichrist of the Internet.
Person 2: "Wow, that sounds really interesting. What? It's an article about a guy who works in Silicon Valley and thinks the internet is the downfall of society? Boo-oring."