It's not an abbreviation.
If you were ever to abbreviate Pakistani, it would be to pak. (it gets a full stop because when an abbreviation ends in a different letter to the full word, you put a full stop, but that's by the by). Paki is an offensive term. Do you understand?
(rnuk http://flickr.com/rnuk, Thu 26 Jun 2008, 14:52, archived)

Its not like I go around calling all coloured people paki's or anything
In fact I can't actually remember the last time I used the word.

I just dislike the fact that people automatically assume you are an ignorant racist if you use that word, even if it is spoken in an entirely unoffensive context.
( shitshitshitshit x_x, Thu 26 Jun 2008, 14:59, archived)

Give me an example of an inoffensive context
using the word 'paki'. Go on, I dare you. I'll shoot you down in flames without even trying.
(rnuk http://flickr.com/rnuk, Thu 26 Jun 2008, 15:02, archived)

"We're out of milk. Is the paki shop still open?"
*dons flame retardant overalls*
( shitshitshitshit x_x, Thu 26 Jun 2008, 15:03, archived)

It's offensive because
PAKI IS AN OFFENSIVE TERM.


BURN.
(rnuk http://flickr.com/rnuk, Thu 26 Jun 2008, 15:05, archived)