Those who keep up with Fortnite news may know that a contest to choose a dance for the Boogie Down emote started back in March, and now that the contest is over and the emote has been made, it's only available to players who choose to secure their accounts with two-factor authentication. Doing so is fairly simple, and doesn't really involve that much extra work on the player's part. As of this writing, enabling this feature and providing a secondary authentication vector, such as agreeing to receive email messages for login, is the only way to obtain the Boogie Down emote.
Opting into two-factor authentication will mean that you'll have to answer an email or confirm your login with an app every time you use a new device or haven't logged in for 30 days. Clearing your browser cookies could also trigger the feature, and it's worth noting that you will have to do a 2FA check the first time you log in after signing up. To turn the feature on, go in your ACCOUNT settings, then head to PASSWORD & SECURITY, then finally go into the TWO-FACTOR AUTHENTICATION heading. From three, you can turn it on for email or in-app authentication.
Fortnite accounts can be popular targets for hackers, since accounts with purchases can often be resold if they're successfully penetrated. As such, enabling two-factor authentication may be a bit of a pain, but it's a smart move for anybody who invests time and money into their account and doesn't want to lose their purchases and progress. You don't necessarily have to be bad at password management or create an insecure password to get hacked; there are many different ways a hacker could get your password, and most of them don't involve getting it directly from Epic Games through a data breach. Mobile gamers could be especially vulnerable, given the wealth of exploits out there that target mobile devices and their always-connected status. This is doubly true because of Fortnite skipping the Play Store; folks who get confused and download the installer from an outside source may inadvertently grab one with a trojan of some persuasion attached, and without the stringent security requirements of the Play Store, it's possible that any sort of security oversight from Epic Games could result in players' information being stolen.