Since this thread has turned into a much better topic, I'll share some of the slang that I was exposed to the last time I went to Monterrey.
"Que pitos contigo?" - Heard this one while walking downtown at night with a colleague. We walk by a bar that's playing mariachi music, and this taxi stops in front of us. Three young adults/highschoolers get out of taxi. One of the girls says, "Let's go in there. They're playing Salsa music.". The male in the bunch goes, "Que pitos contigo? That's not salsa music. Took my fluent spanish speaking colleague a few minutes to figure out what the phrase meant.
"Mamon." I travel to Mexico for business. We go to this potential customer who makes high-end furniture. Now, the backstory to this story is that I have both ears pierced. Those who travel to Mexico will, I presume, understand where I'm going with this. Anyway... I'm looking at some furniture that just got finished with my coatings. I have my safety glasses on my forehead so that I can see clearer. This guy comes up to me, and his Spanish is too fast for me to understand. However, I see him gesture to his ears as though he's talking about my earrings. This makes me think of another experience I've had, and I tell him. "No, no, no... estoy casado. No punjale." (forgive me if I'm misspelling it). He looks at me all perplexed. I then tell him who I'm there with, and we go over. Long story short, this cat is the site HSE manager, and he wanted me to wear my safety glasses, safety shoes, and remove all my jewelry. The gentleman that my colleague and I are visiting tells me what this guy wanted. And then tells me that the next time I see the HSE manager, I should say, "Hola Carlos, mamon!" Needless to say, I would not have been allowed back at the site if I did.
"Esta padre." Apparently, this is the younger generation's version of "the bomb". It was used one night when asking if a particular dining establishment was any good.