What do Cheryl's Tupperware containers represent in the novel, The First Bad Man?

The Tupperware containers represent both Cheryl's organization and also how close she is at all times to cracking into utter chaos. She uses them to eat out of at times because they are easier to clean, but they serve as urinals for her when she breaks down early in the novel. They represent her animalistic nature and how she attempts to cover it up but is unable to fully do so.