In chapter 5, what makes Bobo feel so indignant?

iRutanne nstructs a young African American male she calls Bobo to pick up Hiram's luggage. Bobo does not want to do this, causing Ruthanne to call him by his real name, Emmett Till. This causes him to pick up Hiram's luggage, but he soon tricks Hiram into carrying this own luggage once Ruthanne's back is turned.