Sacar un pedo

As grotesque as it might sound, this expression is utterly effective. Sacar un pedo (sah-KAR oon PEH-though) literally means "to force a fart out". It is used to convey a great surprise or a very scary situation (one that would make you fart involuntarily). If you want to emphasize the size of the scare, you can augment the size of the fart by substituting pedo with pedote, or pedotote, or pedototote, and so on.

Example 1:

Memo: Costa Rica le sacó un pedo al Tri en la última eliminatoria mundialista.
Nacho: Pero como de costumbre, los ticos se la pelaron.

Memo: Costa Rica gave a scare to Mexico in the last World Cup qualifyers.
Nacho: But, as usual, Costa Ricans let it slip.

Example 2:

Pepe: Mi chava me sacó un pedototote. Resulta que leyó mal la prueba de embarazo y creyó que estaba en Barcelona.
Paco: Esas chingaderas tienen un amplio margen de error. Al chile creo que deberías decirle que se la haga de nuez. Igual sí vas a ser papá.

Pepe: My girlfriend scared the crap out of me. She misread a pregnancy test and thought she was prego.
Paco: Those little things have a wide margin for error. Straight up, you should tell her to try again. Perhaps you're actually going to be a dad.

In the image below, un burro le está sacando un pedo al niño.

Chingarle

Disambiguation note: this term is different from chingar and chingadera.

Chingarle (cheen-GAR-leh) means to work hard at something. It is used in expressions such as voy a chingarle un rato más (I'm going to work a little longer) or estuve chingándole a mi tesis del doctorado por cuatro años y todo para terminar escribiendo este pinche blog para gringos que quieren pasarse de lanza y mentar madres cuando vayan a ponerse hasta las nalgas en el DF (I worked my ass off for four years writing my PhD dissertation, all that to end up writing this stupid blog for Americans who want to swear and say insulting things when they get shit-faced in Mexico City).

Just for the record, it takes an average of 5.3 years to complete a PhD dissertation in the social sciences. However, it takes many years more to remove the memory of the silly Renaissance costume that PhD candidates are forced to wear in public in their graduation ceremony.

Pura piña

The use of this expression by non-native Chilango speakers will make any native really proud. It is informal yet not offensive at all. Pura piña (POO-rah PEE-gnah) literally means "pure pineapple". It is used to refer to something fictitious, made up or simply a decoy. Pura piña is often preceded by la, as in la pura piña.

Example:

Colega: ¡No mames, Menchaca!, cómo le has chingado para obtener el puesto de gerente. Ya ni te veo.
Menchaca: Es pura piña. Me la paso tirando la hueva todo el día hasta bien entrada la noche.

Coworker: Holy shit, Menchaca! you've seriously worked your ass off to be promoted to manager. I don't see you anymore.
Menchaca: It's all fiction. I've been slacking all day until very late in the evening.

Guns: la tartamuda & more

La tartamuda (lah tar-tah-MOO-tha) literally means "the stuttering (female)". It is a term popularized by the late actor Miguel Galván. It means gun, and when fired repeteadly, guns might sound like a stuttering person. Be wary of anyone threatening to pull out on you la taramuda. Consider immediately surrendering all your belongings to avoid a blood bath.

Other terms for la tartamuda are cohete (lit. fire cracker), fuego (lit. fire), plomo (plumb), fusca and tola (from pistola). The video below shows the performance of Miguel Galván that made the term famous and also earned him the same nikname, la tartamuda. It's a TV ad for a bank.

De a tiro, al tiro

De a tiro (thee-ah-TEE-roh) literally means "of shot". De a tiro typically precedes adjectives. It is used to emphasize a trait of a person or an attitude.

Al tiro (al-TEE-roh) literally means "at shot". Someone is said to be al tiro if that person is alert and ready, or on top of his or her game.

Cautionary note: It is very different to say de a tiro vs. de a tira, which means "police officer style", and the same happens with al tiro vs. al tira, which means "to the cop".

Example 1:

Benito: No me dí tinta de que me estaba echando lámina.
Gualberto: Estás de a tiro bien pendejo.

Benito: I did not realize she was hitting on me.
Gualberto: You're so fucking oblivious.

Example 2:

Pedro: Reinita, necesito que estés al tiro para la siguiente escena.
Penélope: Tu nomás dí rana.

Pedro: Princess, I need you to be ready for the next scene.
Penelope: I'm ready.

Pedro Almodóvar's movies are highly recommendable, but avoid picking up any expression that you hear in them. It can make you sound really silly if you use it in DF.
 

Cagante

Cagante (kah-GUN-teh) literally means "the one who defecates". It means obnoxious, annoying. If you have to use this word frequently, we suggest you quit your job, switch friends, move to another city or find a new significant other. Cagante is both offensive and insulting. Use it with a serious face to increase its effectiveness.

Example:

Televidente: Es como si las televisoras hicieran un concurso para encontrar a la persona más cagante y luego le dieran a los finalistas el puesto de comentaristas deportivos.
Cuate: No te claves, maestro. Nomás apágale al pinche televisor y listo.

TV viewer: It's like if TV networks had a contest to find the most obnoxious person and gave the finalists the job of sports commentators.
Buddy: Drop it, dude. Just turn the TV off and problem solved.

TV personalities in Mexico (as in any other place) are either worshiped or profoundly disliked. Two of them are Mario Bezares and the late Paco Stanley. In the video below you can see why. And you can also see one of them accidentally dropping what allegedly looks like a little bag with a banned substance.