In the book "The Boy in the Striped Pajamas" by John Boyne, Bruno asks about the concept of outdoor wiping, which reflects his curiosity about the unfamiliar environment and activities he observes. The term suggests a routine or practice related to cleanliness or hygiene outside, but Bruno's innocence leaves the exact meaning open to interpretation, highlighting his limited understanding of the world around him.

Bruno's question showcases the innocence of a child discovering new aspects of life and the language used in his context. The quote "Wiping? What is an outdoor wiping?" captures his confusion and the way he attempts to make sense of unfamiliar customs or terminology he encounters, emphasizing the theme of innocence amidst serious circumstances in the story.