In to kill a mockingbird what practical joke had persuaded the grown ups to have an organized event?

The practical joke would actually be seen as trouble making. In chapter 27, and in my book it's on page 251 and 252. The practical joke were some kids moving all of Miss Tutti and Fruit's furniture to the cellar. Since they were deaf they couldn't hear those kids running around.

Here is a direct quote from the book: "So the Maycomb ladies said things would be different this year. The high-school auditorium would be open, there would be a pageant for the grown-ups; Apple-bobbing, taffy-pulling, pinning the tail on the donkey for children. There would also be a prize of twenty-five cents for the best Halloween costume, created by the wearer."