Agarrón

Agarrar means "to grab". Agarrón (ah • gah • RUN) literally means "big grab". However, on the streets agarrón means "fight", particularly "fist fight". When a person is involved in a fight, that person se da un agarrón (lit. "she gives herself a big grab").

The origin of agarrón is straightforward. When someone punches several times some other person, the former agarra a chingadazos the latter. Agarrar a chingadazos means "to grab with punches". The same happens when someone agarra a patadas (kicks) or cachetadas (slaps on the face) someone else.

Agarrón is used by sports commentators in the media to speak of an interesting and rather balanced match. Typcially, games between Chivas and América (the two most popular soccer teams in Mexico) are agarrones, and from time to time some players se dan un agarrón.  

Hacer changuitos

Hacer changuitos literally means "to make little monkeys". It has nothing to do with monkeys. Hacer changuitos is a colorful way to say "to cross one's fingers". Like in English, it expresses one's desire for something to happen. It's an appeal to good luck.

Example:

Fátima: Neta que si alguien se merece esa chamba, eres tú. 
Lourdes: ¡Haz changuitos! 
Fátima: Por cierto, ¿el bikini es a huevo o es opcional?

Fatima: Honestly, if anybody deserves that job, that's you.
Luordes: Cross your fingers!
Fátima: By the way, is the bikini part of the job requirement or is it optional?

Caminar

Caminar literally means "to walk". However, when used to refer in past tense to a project, an idea, a strategy or an action, it means quite the opposite. If a project, an idea, a strategy or an action caminó, then it stalled and won't be moving forward. 

Example:

Don Ramón: ¿Qué pasó? ¿No que ya estaba sobres para traer a un arquitecto catalán para renovar la vecindad?
Señor Barriga: Hazte. Bien sabes que eso ya caminó. Quería un camarón estúpido.

Mr. Ramón: What's up? I thought you were eager to bring a catalan architect to renovate the housing complex?
Mr. Barriga: Don't play the fool. You know very well that ain't happening. He was asking an insane amount of money.

De piquete de ombligo

De piquete de ombligo is a way to describe a relationship. It literally means 'of poking each others belly button'. Two or more people are said to have a de piquete de ombligo relationship if they get along well and are really close. Mexicans don't go by the streets poking random strangers' belly buttons. They only do it to a rather selective and small circle of friends (and foes). The expression is typically preceded by llevarse (lit. to carry or behave themselves) as in llevarse de piquete de ombligo.

Example:

Profesor: No me gusta darme mi taco en el salón de clases. Prefiero una relación abierta y de amistad con mis estudiantes, de piquete de ombligo. 

Coordinador: Nada más no vayas a picarle el ombligo a ninguna alumna. Si no, te cae la voladora.

Instructor: I do not like to pretend to be unreachable in the classroom. I rather developing a friendship with my students, really casual and familiar.

Coordinator: Just make sure you don't actually poke their belly buttons. Otherwise you'll face disciplinary measures.

  

Azotarse

Azotarse literally means to self-flagellate. In Mexico, it also means to make a big drama that does not match the situation. Of course, if someone se está azotando or not is in the eyes of the beholder.

Example:

Remi: Están súper pendejos si creen que yo voy a pagar el pato.  Ya sé que sólo quieren sacarme un un pedo, pero a mi me vale verga, ya verás que se van a cagar pa'dentro cuando me desquite. 
Señor Vitalis: No te azotes y prepárate para la próxima función.

Remi: They gotta be fools to believe I am taking this shot. I know they just want to scare me, but I don't  give shit about it, they will poop their pants when I take revenge.

Mr. Vitalis: Chill out and get ready for our next street performance.

Remi ("Nobody's Boy") is a cartoon  that was very popular in Mexico despite its extremely  azotado contents.

En el ácido

En el ácido literally means 'on acid', as in 'on LSD'. It's an expression that has nothing to do with the actual consumption of illegal drugs. En el ácido is used to refer to an extremely upset or perturbed person, usually by an undesirable  situation. The person en el ácido  often behaves as if he or she were hallucinating with the help of LSD: frantic looking eyes. sweating, not-making much sense, etc.

Example:

Leticia: Creo que está en el ácido. 
Juanjo: ¡Puta madre!, y cómo no si le dieron bajilla con la laptop donde tenía todos los documentos de su chamba. 

Leticia: I believe he is utterly upset.
Juanjo: Geeez, I bet he is, he's laptop was stolen with all the documents from work.

De bote pronto

De bote pronto (the BEAU • teh PRAWN • taw) literaly means 'after a fast bounce'. It is used to convey that something is done on the spot, without much time to prepare, without giving it chance to bounce away. Agarrar de bote pronto means to give an opinion or decide a course of action right away, i.e. to shoot from the hip.

Example:

Maribel: El licenciado es súper mameluco pero las agarra de bote pronto. Se vé que lo van a hacer gerente regional de volada.
Cinthya: ¡Bájale! Ese cabrón no sólo le echa mucha crema a sus tacos sino que a veces ni le cae el veinte de las cosas.

Maribel: The boss is very uptight but he's really fast solving problems. I'm sure he'll be promoted to regional manager in the blink of an eye.
Cinthya: C'mon! That dude not only is a show off but sometimes he doesn't get what's going on.