If you need a guide to Twitter, one of Thursday's trending topics should help.
And if you're already a hardened Twitter veteran -- no egg avatars, please -- you'll know that Tehran is trending because of a deadly building collapse in Iran's capital, while Steve Carell is trending after a massive trolling from "The Office" star.
Social Cues is our look at what's trending across social media. Here's what people are talking about on Thursday:
#ThingsToKnowAboutTwitter: Before you join the keep-it-terse social network, there are a few things you ought to know. The trending hashtag on Thursday gave some warnings that Twitter veterans are all too familiar with. Like how addictive the social network is. Or that your favorite shows can and will be spoiled on Twitter. And most importantly, if you do something wrong, people will never forget it. Good luck out there!
Denis Istomin: The little-known tennis player defeated six-time champion Novak Djokovic at the Australian Open on Thursday in a shocking win. Djokovic was expected to win it all for the seventh time, but was eliminated in the second round by the Uzbek athlete. Istomin was ranked 117th in the world, and hasn't knocked off a top 10 player since 2012. The unlikely winner is trending on Twitter with people still amazed at the underdog story.
Tehran: Iran's capital is trending on Twitter after a burning high-rise building collapsed, killing 30 firefighters. Officials are still investigating the cause of the blaze, which destroyed the building in a matter of seconds. Emergency responders are digging through the rubble to find any survivors, according to state-run media.
Libya: US Air Force B-2 bombers hit ISIS camps in Libya overnight, defense officials said. The airstrike came on President Obama's final full day as the US commander in chief, after having been approved several days ago, according to CNN. The news is trending on Twitter as people comment on the ongoing fight against ISIS.
Steve Carell: "The Office" star pulled off the ultimate troll move on Twitter on Wednesday. He tweeted out, "Breaking News: 'The Office' returning to NBC," and immediately after, broke everyone's heart by revealing it was a joke -- the network is instead reviving a different sitcom. The bait-and-switch was trending on Facebook by Thursday morning, with throngs of disappointed fans. This is worse than the "Scott's Tots" broken promise.
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