A pink flamingo is a three-dimensional plastic figure of the flamingo bird, most often with metal sticks for legs, often seen in people's yards. They originated in 1952 as a flat yard decoration by Union Products; four years later, the company hired Don Featherstone to make three-dimensional versions of their flat decorations. The type he made first was made of foam plastic and proved too easily chewable for dogs and other animals, so a hard plastic version debuted in 1957. He modeled their poses -- a pair with one bird's head raised and the other lowered as if feeding -- on photos in National Geographic magazine. The birds became extremely popular yard ornaments, and Union Products manufactured three-quarters of those sold before 2006 when Union Products closed. (That brand had Don Featherstone's signature under their tails after 1986, and has a yellowish beak with a black tip.) In 2007, HMC International LLC bought the rights and the molds to continue manufacturing Union Products' flamingo.

In the 1970s, an attempt was made to give the birds more realistic yellow legs, but these hardly sold at all; the metal stick legs were brought back and even retained in a white version of the ornaments known as the "snowmingo."

The birds have gone up and down in popularity at different times, but they have a sort of kitschy cool now after more than 50 years, leading to all kinds of variations -- different not-found-in-nature colors and patterns (including a blue flamingo intended specifically for neighborhoods that had prohibited having pink flamingos on the lawn), holiday flamingo statues, lighted versions of the bird, and other flamingo products; even businesses such as "The Original Flamingo Surprise" and "Flamingos by the Yard," which specialize in surprising people by filling their yards with the statues. Don Featherstone wrote a tongue-in-cheek 1999 coffee-table book about his creation called Pink Flamingos: Splendor on the Grass; he had become the president of Union Products by that time, but retired the next year. The band Love and Rockets have a song called "Pink Flamingo" and Rebecca Lynn Howard has one called "Pink Flamingo Kind of Love."

Pink Flamingoes is also the title of a really freaky 1972 John Waters movie about two families competing for the title of "the filthiest people alive," featuring sexual acts with chickens and Divine eating dog shit. Presumably the movie uses the title to imply the tackiness some people associate with the lawn birds.

Sources:
http://www.chron.com/content/chronicle/features/97/03/16/pink.html
http://earthdude1.tripod.com/pink_flamingo/index.html
http://www.msnbc.msn.com/id/15515764/
http://www.forbes.com/business/2006/11/26/don-featherstone-flamingo-cx_mk_1124autofacescan03.html
http://www.usatoday.com/news/offbeat/2007-06-01-flamingo_N.htm
http://sculptureceramics.suite101.com/article.cfm/the_pink_flamingo_as_american_icon
http://ezinearticles.com/?Extinct-Don-Featherstone-Pink-Flamingo-to-be-Resurrected&id=946050
http://www.sun-sentinel.com/features/lifestyle/sfl-hg20flamingooct20,0,4474139.story
http://www.imdb.com/title/tt0069089/