Maniac prepares himself for another trip to the McNabbs'. Describe what he does to prepare. Why does he have to prepare?

Before Maniac Magee visits the McNab home for a second time, he agrees to attend Piper's birthday party under one condition. Maniac insists the Piper allow him to bring a guest to the party. Maniac struggles to understand the racial divide in Two Mills and believes that bringing a black person to the McNab residence will prove that black and white people have more in common than they think. Maniac hopes to ease the racial tensions in his community by taking Mars Bar Thompson with him to the McNabs'. Maniac must prepare to take Mars Bar over to the McNab residence by convincing him to cross Hector Street, which is something Mars Bar has never done before. After daring Mars Bar to cross the street, Maniac takes him to the Pickwells' home first to give him an opportunity to see the best of what the West End has to offer. After briefly visiting the Pickwells' comfortable home, he takes Mars Bar to the racist McNab residence for Piper's party. Unfortunately, things do not go as planned, and a fight breaks out after Mars Bar comments on the nasty smell of the McNab home. Maniac discovers that ending the deep-seated racism in Two Mills is much more difficult than he expected and will not happen overnight.