The only real racial slur for white people. Pronounced "how-lee"; taken from the ancient Hawaiian.
You may think that you know racial slurs for white people: honky, cracker, redneck. However, these are regularly shrugged off by whites worldwide. There are several reasons. The most basic is that whites are a rather heterogenous and include many despicable groups; most whites think of themselves as superior to the poor "crackers."
To understand the other reasons you have to look at where the word comes from. When Captain Cook first came across the Hawaiian islands, the native people viewed him as a god due to correlations between his arrival and various myths, as well as the superior air with which he carried himself. They called his crew "haole," which means "no breath," because the Gods did not have to breathe. Over time, this term simply came to mean white people in particular.
This is not so bad; there have always been insulting words for whites. However, in Hawaii whites lack the power and numbers they seem to have everywhere else. White people (I am one, despite the moniker) make up only 29% of the population, which is less than the percentage of those of Japanese descent alone and less then half the percentage of Asians. The majority of economic power is currently held by non-whites as well. Our politics are dominated by people with Japanese ancestry; we currently have two Japanese senators, Daniels Inouye and Akaka.
All this means that in Hawaii white people are still seen as being rich powerful assholes without actually having wealth or power. I have taken my share of abuse for having light skin. "Fucking stupid haole" is perhaps the harshest comment I have ever received. The term "haole" is at least the equivalent, in terms of hatred and derision, of "nigger," but is actually more akin to early usage of the term, wherein its insulting usage was sometimes ignored. Haole can mean a descriptive term for whites but most people object to that. The only person I don't consider haole an insult from is another white, unless it is clearly used in jest.
In other words, slurs only really exist for groups that are minorities and lack power. It is possible to insult most white people, but not through slurs. No, only in "the aloha state" are there slurs for white people.
Apparently I misspelled Captain Cook's name when I first posted this. Thanks to Boldra for pointing that one out. The name Cooke actually refers to a missionary family that settled in Hawaii over 100 years ago and now owns more stuff here than you can imagine.