You’re a linguist, Matt?
For a couple of years, I was referred to as guero culero by my Nicaraguan coworker. All in good fun, of course. We also played cucaracha futbol (that’s soccer with a dead waterbug,) but y’all probably didn’t want to know that.
This is the best suggestion offered so far.
SoulFrost - I thought assholes were kinda brownish? 
Well, I majored in linguistics, but this comes from my minor in Hispanic studies.
My father’s Hispanic employees used to call him Viejo. He thought it was Spanish for “Bill.”
And if they call you Gordo, it’s not because they think your name is Gordon.
OK, you got me. Accents are a little too much work for my liking. Anyway, the point remains that they’re calling me it and it’s a generally lame thing to do.
The word is actually “güero”, signifying that the U is pronounced. Next you have to remember that hard /g/, along with the other voiced stop consonants /b/ and /d/, undergoes lenition in many circumstances, reducing all three to fricatives or approximants. This particularly happens when the consonant is between two vowels, giving a bilabial fricative for /b/, a dental fricative for /d/ (much like the TH of English “there”), and a voiced velar fricative for /g/. The latter two, in casual speech, can be softened to the point they disappear - note that, for instance, the name of the United States is “Estaos Uníos” in casual speech. So /wero/ is to be expected at least in rapid or casual speech.
Um, what? 
I recently began studying Kartvelian, Svan specifically, and having to learn all about plosives and frication and glides and ablaut and inflection is making my brain hurt. You sound like you actually understand all that stuff, so you give me hope.
Ah, I see that Excalibre is up on it, as well. Kudos.
Depends on the asshole 
Tell them to stop.
OK smart guy, how come the gals at the Mexican restaurant call me “El /whahpo/”?
I think you misheard them. They were calling you el vano.
They can’t afford eyeglasses?
They think you are a large hamburger. With cheese, presumably.
Ah, a Whopper. Yes, I am!
It has been my experience that one should be discreet regarding such…characteristics. If it becomes too widely known, you are constantly beseiged by oversexed women who view you as nothing more than an object of their depraved lusts. This can have enormous impact on your self-esteem.
I travelled in Mexico a good deal as a kid, with both parents fluent in Mexican Spanish, and will back up Chotii’s observation that the nickname is a cultural norm in Mexico, particularly with physical traits. I was small and light skinned, so “Guerita.” It’s a cultural difference, to do that immediately, and foreign to American thinking. We Americans think it’s a label, and bad, to distinguish by physical traits. I don’t get that from the way Mexican culture applies it, because Mexican kids get the nick’s “Gordo”(big), and “Flaco”(skinny) as well. It’s not considered rude to give physically indicative nicknames.
Here’s a site that has a bit of info about the difference:
I worked in a catering kitchen here in NC, and the majority of the staff were Mexican guys, and all from the same city in Mexico. Everyone had a nickname (yes, there was a Nacho, short-and-fast for Ignacio). Another common one is Chuy for Jesus. Two guys were brothers, and the lighter complected one’s nickname was Guero.
I got Guerita again, didn’t offend me at all because I know the nick thang, and just told em I preferred my Other nick, coincidentally in Spanish, but given by a bunch of non-Hispanic guys years before; “La Gran Pelliroja” (The Great Redhead). They all laughed and said, “Yep, that’s better!!! Ha Ha!!!” So that stuck. It was an endearing term, one that was like Yer Name Here.
I can understand the point of view that Guero is like Whitey, but when I asked about it, it was explained as Blondie. So, perhaps just see the nickname thing and give a better/more fun one, that will stick.
I wish I could offer a site that would explain the tradition better, but I couldn’t find one that explained it well. Some inklings of the skin color class of Mexico, which is a bit different in it’s description than ours in the US. I’d love more explaination.
And if they call you El Jefe, it’s not because they think you’re in NOFX.
In fifth grade, I had a friend whose family was from Mexico. Her older sister was light-skinned and had light brown hair, so the rest of the family called her “Guera”. I don’t even remember her first name anymore, only her nickname. :o
Some of my relatives are Mexican, and I recall one of my aunts referring to the youngest and chubbiest of my cousins as “los gordos” (the fat ones). No one was offended AFAIK. Also I have a co-worker whose nickname for her youngest son is Gordo- as he grows older, he has indicated a preference for his given name.
I suggest you listen to the song “Que onda Guero” by Beck (from the Guero album) for his take on this subject.
You must look then like the bandito from the “Three Amigos”
And if they call you “El Supremo” keep your eyes open for cannon fire.
Um, not sure… post a pic!
Spanish spoken in Spain was hard for me, as the only Spanish I have ever spoken is Mexican! There is definitely a difference…
Seems to me that, far from being hostile, their use of ‘guero’ for you (the OP) signifies some sort of camaraderie with or group acceptance of you, since, as has been explained, that’s what everyone does in Mexico (that I know of, likely S. American countries as well - I have no idea about Spain and I gathered that the co-workers aren’t from Spain anyway) and of course it’s been carried here with the rest of the culture. It IS acceptable practice in that case. Viridiano’s family is Mexican and they all do that do each other, in quite a loving manner. The light-skinned uncle in the family (not actually white at all) is indeed Tio Guerito, and is called that so often that for the first 2 years, before I caught on, I seriously thought that was his name. They have a strong cultural identity and no real reason to subvert it - they haven’t spent the man-hours we have here philosophizing and arguing over whether we should pretend physical characteristics attributed to race don’t exist. I’m also pretty sure that ‘some americans could get the wrong idea’ isn’t really a strong reason.
So you of course have every right to ask them to stop, but likening them to ‘degenerate fucksticks’ for adhering to their own culture is going too far. Unless you’re one of those who believe that everyone who lives in America has to forget about their own culture to the point where they embrace even its aspects that look upon their own customs as negative.