The word Paki isn't racist or offensive but the way it's used is. Paki was/is a shortened term to describe pakistani's but it's used an insult to asians so that's where the problem is.

What I don't get or understand is the term nigger, it's fine for coloured guys to call each other nigger but if someone else does it it's racist, I view nigger as being hugely racist and that's because of how it's used, it confuses me though.