As long as I live I will never understand teenage boys...specifically my little brother Shawn

I just need to get this off of my chest. He got his grades back from school and had all Bs and Cs so we were so happy and going to get his temps and start letting him drive. Today he breaks down and tells me he got a D in auto body. Not english or math or anything else but he picked this training because he wants to do it when he grows up. Ugh and by the way so ready for Friday but wish I didn't have to work Saturday.