The Flamingo Who Forgot

A flamingo forgets something she was trying to remember--can any of the animals help? A flamingo stood in the middle of the lake, on one leg so she wouldn't forget. But, oh dear, she's forgotten what she shouldn't forget. A succession of animals comes past with some suggestions, apart from the hyena, who just laughs at her. Is it bath day that she's forgotten? No. Is it the Jungle Dance Contest she's forgotten? Nest-building Day? The Swimming Gala? No, no, and no. Finally another flamingo comes past--can he tell her what it is she has forgotten?