Urdu speakers of Karachi use it for us. I think it means we are akhroat-headed i.e dumb. We are not dumb but our rural people are surely simple-minded folk who can be easily tricked , brainwashed and manipulated.
You people call us Pathanis, we dont use the word for ourselves. You will call me Pathan in a conversation, i wont interrupt you, it doesnt mean it is the correct word. Beside word Pathan is part of Urdu literature, word Pashtun/pashtana is absent from it.
Word Pathan was coined by Hindus of Hind and subsequently by those who converted from Hinduism. In the Farsi literature of Delhi Sultans and Mughals, word Afghan is used for us. Pashtun/Pakhtun is the most proper word, Afghan comes next while Pathan is an alien and derogatory/improper word.