Dad drives August to the graduation ceremony at the auditorium. They arrive early, so they sit in the car and listen to music. August messes with his hair and Dad comments on how short it is. August says he thinks the shorter hair makes him look more grown up. Dad can barely believe that August is graduating fifth grade, and August reminds him that he started the year with the Padawan braid. Dad admits that while he didn't hate the Padawan braid, he did hate the astronaut helmet. August offhandedly says that he was upset when it went missing, and Dad casually admits that he threw it out.
The fact that August's hair is short right now highlights just how much he's grown up and become more comfortable with himself over the course of the novel. Though he can't wear baseball caps anymore to cover his face, he now also chooses to not cover his face with his hair. When August also says that he thinks the short hair makes him look more grown up, it shows too that he no longer fears being mature and actively wants to be seen that way.
August is livid. Dad clumsily explains that he couldn't handle August covering his face anymore. He was sad that August was sad when it went missing, but he didn't think it was good for August. Dad takes August's chin in his hand and says that he loves August's face and it broke his heart to never see it. August is quiet for a minute and then asks if Mom knows. Dad quickly says she doesn't, which makes August start laughing uncontrollably. Dad swears August to secrecy and August jokes about using this information as leverage to get a new Xbox and a car.
When August proves willing to put aside his anger and forgive Dad for throwing out the helmet, it shows that he understands that Dad was only trying to help him and push him towards being more comfortable with who he really is. By insisting that it's a secret from Mom, Dad makes August feel more adult by making him privy to adult secrets.
August and Dad see Jack approaching, so August starts to get out of the car. Dad confirms that he's forgiven before he lets August out. Before Dad can leave, August runs back and quietly asks Dad to not kiss him after graduation as to not embarrass him. Dad says he'll try his best, but says that Mom probably will kiss him anyway.
Again, Dad's agreement to August's requests shows that he's perfectly willing to do what he can to help August feel adult and mature, even if it means not showing affection to his son like he clearly would like to.