A group of flamingos is called a flamboyance.
Why it is true
Although the technical term for a group of birds is flock or colony, the specific collective name poetically recognized for flamingos is flamboyance, a direct reference to their vibrant colors and exhibitionist behavior during mating.
Source: Smithsonian
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.