Why is Scout walking home from the play in her costume?

Scout had to dress up like a ham because "Mrs. Grace Merriweather had composed an original pageant entitled Maycomb County: Ad Astra Per Aspera."  Mrs. Merriweather wanted to highlight "the county’s agricultural products," which included pork.  During the performance, Mrs. Merriweather was to call out "Pork!" as Scout's cue to enter the stage.  Scout was to enter dressed up as a ham.  Her costume was made from

"chicken wire and bent... into the shape of a cured ham. This [was] covered with brown cloth, and painted... to resemble [ham]."

When the pageant arrived, Scout missed her cue.  She sat down near the stage and fell asleep.  When Scout woke up, Mrs. Merriweather had already called for her several times.  Scout went out on the stage, even though she had already missed her cue.  Later, Mrs. Merriweather informed Scout that she "had ruined her pageant."  The woman's cruel words "made [Scout] feel awful."  When it was time to go home, Jem suggested to Scout that she take off her bulky ham costume.  Scout decided to wear it home to "hide [her] mortification."