When someone tests you with a rude question, answer the reasonable version of it.

Most rude questions contain a real question wearing a bad costume. Answering the sharp version means fighting on ground somebody else chose, and you lose either way: angry or rattled. Answering the reasonable version underneath it takes the point away from them without any visible effort, and it often turns out to be a question worth answering.

When somebody tries it, repeat back the sensible form and reply to that. If someone asks why you even bother, answer what you get out of it. Say it evenly and move on before anyone has time to escalate.