The flamingoes at the St. Louis Zoo were kept in the World's Fair flight cage before it's recent remodeling into a native Missouri wetland display.
I'm probably indulging in anthropomorphism by saying this, but it sure did seem like the birds here were showing off for me - whenever I lifted my camera to look through the viewfinder one or more of them would stretch out for me. Now it's possible that they thought my gesture was a challenge of some kind, or that I was getting out food for them. Who knows what they were thinking? The behavior sure was amusing whatever it was.