Hubbub is a fun, rhyming word for an uproar, a brouhaha, or another crazy situation that has gone completely higgledy-piggledy.
No one would say, "What's the hubbub?" at the library, unless it was the loudest, most bonkers day ever in a place that is usually quiet. A hubbub is chaotic, disorganized, loud, and distracting. Sometimes, hubbub can mean a controversy, as in "What's the hubbub over this new law?" If you like peace and quiet, stay away from hubbubs — a word that sounds as loud and unruly as its meaning.