Some Slang Used In Mexico
I don't know it all, but here are some of the slang words and uses I have picked up in Mexico. Some of them may actually used in other Latin American countries as well.

Güey- Probably the most used slang in Mexico. It is like "dude," and is used ALL the time (pronounced almost like “way”).
Pinche- fucking (adj.)
No manches- No way! Not to be used in formal situations.
No mames- No way! The cussword version. Definitely do not use this in formal situations. literally it basically means don't blow me.
Mamada- blow job
@- used when a word can be male or female, to represent both the “O” and the “A” in the word.
Güerr@- Blondie. Almost all gringos are also often called güeros, and the term is also used for fair-skinned or light-haired Mexicans. People often call me Güerita.
A poco- Oh really? Or You don’t say.
Valorse Madre (ie Me vale madre!) I could give a fuck. Reflexive verb.
Que poca madre, often shortened to Que poca. Basically What a jerk!
Squinkle- Brat. This is what Nerds candy is called here and also refers to bratty or spoiled kids.
Junior- rich kid. Especially used for males, and especially for young men who have family money and power.
Chela- a beer. “Vamos por una chelas!”
Cabrón- (n.) Asshole. Can also be used as an adjective about something either really bad or really awesome.
Cañon- Nicer way of saying something is really bad or really awesome. “Está cañon”
Coger- To fuck. In Spain, this means to pick up. In Mexico, it is used as a dirty word, so people use the word “recojer” for “to pick up.”
DF- Distrito Federal, what Mexico City is called in Mexico City. Everywhere else in Mexico people call it either the DF or just México.
Fresa- kind of like Valley Girl- it means rich people, especially females. It can also refer to a bar or a neighbourhood.
Niño bonito- kind of the male equivilant of Fresa, but also kind of like Pretty Boy.
Chido- Cool
Padre- Neat
¿Qué tal?- What’s up? Answer: ¿bien, y tu?
¿Qué onda?- What’s up? Answer: Nada, güey. Tú, ¿cómo estás?
¿Cómo te va?- How are you doing? Answer: “¿Bien, y a ti/usted?”
Chingar- To fuck with. “¡No me chingues, güey!”
Chingón- Tops (informal). “vente a la fiesta, está chingón!”
Chinga su/tu madre- Fuck your mother. The worst thing you can say to someone. Do not say this unless you are talking about someone else (saying Chinga su madre is like saying Oh, fuck him!) or if you are itchin’ for a fight.
Tener ganas- to want to do something (tengo ganas de ir al cine)
Darse huevo- to feel lazy. Informal- literally means your balls were so heavy it made you lazy (me dio huevo, I didn’t feel like doing anything)
Huevon@-Lazy (informal)
Mens@- stupid
Chinas- curls. Someone who has curly hair is chin@ or chinit@. This also refers to someone who looks Asian.
Codo- Cheap, as in a tightwad person. Literally means elbow. If you want to indicate that someone is cheap, you tap your elbow with your open palm.
Reventón- Party (not used like fiesta, used more like we use “to party”)
Desmadre- Fucked up situation or mess (informal).
Puta- Whore. Also used as an exclamation like Shit! Or Fuck! Extra strong: ¡Puta Madre! People in more formal situations also say “’uta,” which is considered OK, even in business meetings.

A few other very slang things to say that are used in such various ways that I can't explain them to you:
Que pedo
A huevo