So this is one of my many difficult scenarios I need help with!  I am the "Stepmom".......
Boy comes home from basketball tryouts, previously knowing he would not make the team due to an injury.

Dad says, “So, how did it go?”

Boy says, “Shut the fuck up” as he walks upstairs.

Stepmom says, “Oh my God……” not yelling but in disgust because of the disrespect he gave his father.

Boy tells Stepmom, “Fuck you”.

Dad says to Stepmom, “Ya had to piss him off didn’t you! I told you he would probably come home upset.  You are so rude!”