gaggle
A noisy, somewhat messy group, especially of geese or people.
A gaggle is a group of geese, especially when they're on the ground or in the water rather than flying. The word captures something about how geese act when they're together: waddling around, honking at each other, creating a noisy commotion. If you've ever seen geese at a park pond, you've seen a gaggle.
People borrowed this word to describe groups of people who remind them of geese, usually because they're loud, chatty, or moving together in a somewhat disorganized way. A teacher might smile at a gaggle of students walking down the hallway, talking excitedly about lunch. You might see a gaggle of tourists clustered around a famous statue, all craning their necks for photos.
The word has a playful, slightly silly feeling to it. Nobody uses gaggle in a formal or serious way. You wouldn't say “a gaggle of scientists” at a conference, but you might say “a gaggle of kids” at a birthday party. When geese fly in their famous V-formation across the sky, by the way, they're called a skein or a wedge, not a gaggle. But honestly, gaggle is much more fun to say.