To Flounce (verb) is a term specific to the Flop House Facebook Group, meaning to leave said group with a post explaining why he/she has left the group, esp. phrasing it in the manner in which they have all failed said Flouncer (n.) and maybe, just maybe, this last desperate action will cause them all to to take a good hard look at themselves. Preferably taken by someone whom the Facebook group has only the vaguest idea was in the group in the first place.
Particularly memorable flounces lead to long memorial threads.
A flounce proper is not to be confused with a disagreement, a heated argument, or someone merely leaving the group.