I taught my brother a cuss in sign language and we kept doing it at one another.

Mom: You are not allowed to flip each other off or do rude gestures to each other inside the house. I can't control what you do in school but if you get in trouble -

Brother: They're all idiots, they don't know sign language.

Me, at the exact same time: The teachers aren't smart enough to know sign language.

Mom: *staring off into the distance with a bleak expression* What have I done?