This is a very offensive racist insult. Do not use it. Do not write it to be short, and do not repeat it as a joke. In Britain, some people clipped Pakistani — or pulled a short form out of the country name Pakistan — and used it as a nasty name for a person from Pakistan. They also threw it at people from India and other parts of South Asia who were not Pakistani at all. That is part of the harm: it lumps many people together and insults them. It can name a person or sit in front of a noun (this shop, this person). Both uses are insults. You may still meet it in news about hate crime, or in old books and films. That does not make it all right to say. If you need to talk about someone, say Pakistani, or Indian, or South Asian — the real, respectful word for who they are. Though actually, a few people have tried to take the insult back inside their own community. That is their business, not a student’s licence to use it.