Reporting from Mexico City — Daniel Navarrete greets friends with what seems an unlikely term of affection — he calls them "ox."
Navarrete, a 19-year-old snack vendor, isn't being rude. Go anywhere in Mexico City and you can hear someone calling someone else "guey," which means "ox" or "slow-witted." The word, also spelled buey, once was an insult, but it has morphed over years of popular use to become Mexico's version of "dude" or "bro."
A guey (pronounced "way") can be a spiky-haired boy, a stubbly-chinned jitney driver, a college student with a ring in her nose. Take a table near a bunch of Mexican teens and it often sounds as if all other parts of speech were designed to transport you from one "guey" to the next. Even narco thugs have scrawled the word as an epithet in threatening banners, misspelling it wey.
"Everyone I talk to, it's 'guey,' 'guey,' 'guey,' " Navarrete said as he pulled a shift selling potato chips one recent afternoon with a friend named Edgar Martinez, who said he, too, uttered the term "all day."
"It's a custom of Mexican culture," Martinez, 33, said with a shrug.
It can be like that in Mexico, a land so rich in slang and wordplay (much of it salty but freely used) that a newcomer armed with book-learned Spanish might feel he had studied for the wrong test.
Although it never hurts to know the "hola!" greeting, you may be hailed with a slangy "quihubo!" a Mexican version of "what's up?" Someone who shouts "aguas!" isn't announcing the arrival of water; she's telling you to watch out. (It's aimed a lot at chamacos, slang for "children.")
The oft-heard "no manches!" literally means "don't make a stain," but it's used to express incredulity, as in "get out." A person with lots of lana, or wool, isn't fuzzy, he's rich.
Some Mexicans worry about a proliferating usage of slang terms once considered too coarse for common use. They blame the looser talk on television and radio, as well as social changes that have given Mexican women equal access to colloquialisms, even raunchy ones.
"A narco, a rube and a yuppie all speak alike," said commentator Guadalupe Loaeza, who said she has been shocked by the crude words that sometimes pepper the e-mail she receives.
"There's a laxity of language that I would say is almost offensive," Loaeza said. "We've gone too far to the other side."
Still, one can marvel at Mexico's genius for remixing the simplest Spanish words into any number of colloquialisms that veer puckishly from the mother tongue.
Take "madre." The word for "mother" has enough vulgar usages here to have given Freud a Mexico fixation. If everyone loves his mother, how to explain the fact that the word can mean something that is very, very good or, seasoned slightly differently, something that is very, very bad?
(At the same time, "padre," or "father," is often used to denote "cool," though the younger set seems to favor the more recent "chido.")
" 'Madre' is so characteristic of Mexico. It's a matriarchal society in part because it's such a macho society. The two go hand in hand," said Concepcion Company, who led research on a new dictionary of so-called Mexicanisms.
Company, who was raised in Spain but has lived in Mexico since the 1970s, said Mexican colloquialisms have their own personality, playful and pun-soaked and full of double meaning. Unlike places where Spanish curses are often scatological or tinged with religion, Mexican oaths favor the sexual, she said.
The flexibility of Mexican slang allows even some profanities to be stretched and refolded into a mind-boggling variety of uses, some of which no longer carry an X-rated punch. "It's a magical word. A change of tone, a change of inflection is enough to change its meaning," Mexico's revered man of letters Octavio Paz once waxed about a ubiquitous verb that won't be waxed about here.
The lingo of Mexicans is also increasingly influenced by the Internet and social networking sites, bringing even more English terms to a country where stylish clothes are advertised as "muy fashion" and people bid farewell with a clipped "Bye!"
To go on Facebook, for example, is "facebuquear." Twitter devotees keep us posted by "tuiteando," or tweeting. Someone in need of a new look might be told to "fotoshopeate," or "Photoshop yourself."
Martinez, the snack seller, knows that some may be tut-tutting over the creeping coarseness. But he said the key is knowing how slang will be interpreted. To illustrate, he barked a familiar crude epithet at a young acquaintance nearby. The youth winced as if splashed with something foul.
But "guey" — no, that is something else. "It's an endearment," Martinez said, as benign as a soul handshake.
When it was time for a visitor to leave, his friend Navarrete gave a friendly fist bump and then offered the same farewell his closest buddies get.
"Take care, guey," he said.