The popular Fortnite dance emote involving a side-to-side arm swing is Floss.
The Floss emote is based on the dance in which a person swings clenched fists and straight arms from behind the hips to the front, alternating sides while moving the hips in the opposite direction. The motion was nicknamed “floss” because it resembles pulling an enormous piece of dental floss between the legs and around the body.
The dance became widely known after Russell Horning, often called the “Backpack Kid,” performed it in viral videos and during a 2017 Saturday Night Live appearance with Katy Perry. Epic Games later included Floss in Fortnite Battle Royale as a Season 2 Battle Pass reward in 2017.
A common mix-up is confusing Floss with Fortnite’s other dance emotes, such as Electro Shuffle or Breakin’. Floss is the one defined by the rapid alternating arm-and-hip swing, and its popularity helped spread the dance far beyond the game.