At lunch, Albert says he used to call Ally the Flying Tiger after pre-World War Two airplanes with shark teeth painted on the nose. Pilots used to repaint the planes, which made the enemy think there were more than there actually were. Albert says that Ally used to figure out how to "repaint" herself for teachers. Keisha asks if he had a nickname for her. Albert is quiet and then says he called Keisha The Baby. Keisha is offended, but Albert says that when Keisha is quiet, she takes everything in, but when she's loud, she gets what she wants. Ally says it's perfect.
Albert's nicknames for his friends show that he's far more interested in the world around him than Ally has thus far given him credit for. He definitely has Ally figured out, even before they'd said more than a few words to each other. All of this works together to suggest that Albert desperately wants to connect and is very tuned in to the people around him.
Ally asks if Albert has a nickname for himself. He does; he calls himself the Elephant. It's not because he's big or because he has a good memory, it's because elephants have thick skin. He says that happy and sad often look the same on an elephant. Ally thinks that she's believed Albert doesn't feel anything, when really, he feels everything.
Albert's own nickname confirms this: he prides himself on his ability to look as though he's not bothered by things, because it makes those things easier to deal with. With friends, he doesn't have to pretend.