This is the term they use in prison when someone gets hanged.
There were many hangings in Berlin, in which the victims would twitch and jump at the end of a rope...hence, doing the "Spandau Ballet." Also, there were frequent suicides of Nazis being held for trial at the Spandau prison. A hanged person tends to jerk around and "dance" if the death is caused by strangulation (and not a snap) they say. As the years went by it progressed to floorless dance or waltz or the air rumba.
"They found Rosco in his room doing the floorless waltz, the air rumba or some call it the floorless dance."
The Reddit equivalent to Discord's "Whitename":
A demi-derogatory term for the stereotype of a user who's new to a subreddit, and didn't pick a flair yet, hence the name. The flairless user is prone to breaking the rules because they don't realize what they are, miss out on a lot of the subreddit's inside jokes, and often say stuff that don't make sense because up until joining the subreddit they only participated in the cancerous and/or childish part of that fandom.
User A: "Does User C's post make any sense to you?"
User B: "No, not at all. But he's a flairless so I can't say I'm surprised."
User C: "...I'm right here."