The pinkest lawn ornament in history has an equally colorful history. Even though the real birds -- asymmetrical stance and all -- hail from Florida, their plastic counterparts were invented in Leominster, Massachusetts by sculptor Donald Featherstone circa June 23, 1957. Yes, "Featherstone" was indeed his real last name.
Featherstone was honored with Pink Flamingo Day for his contribution to good taste (and irony) in 2007 by the mayor of Leominster, which he got to celebrate annually with his community until his passing in 2015. On top of his own holiday, Featherstone even got a sentient pink flamingo named after him in Disney's 2011 CG animated Gnomeo & Juliet movie.
Pink flamingo patrons can commemorate the day by peering out into their lawn. Those lacking the ultimate grass-cessory can simply read these comics.