I don't disagree
A fancy way of saying, 'I know you're wrong, and I think you're an idiot.'
'I don't disagree with your dumb comment,' he said, while smirking.
She said, 'I don't disagree with your stupid idea,' and then left the room.
He texted me: 'I don't disagree with your dumb plan.' I replied: 'You're a jerk.'