Naco

Naco = low class, uncultured.

The word naco is closely tied to Mexican society and culture. It refers to a thing, a person or their behavior that is considered low-class, without refinement, crude and uncultured. The standard for what qualifies as low-class will depend on the speaker's background, upbringing and social milieu, naturally. Use with caution, as the word can give offense.

Here are something media and artistic entities that may qualify.

¡Qué naco! What a naco thing you have just mentioned, shown me, confessed to.

Un naco

Un naco is someone who displays naco traits or preferences. Some Mexicans consider anyone poor with piel morena to be a naco almost by definition.

Nacada

Una nacada is something a naco would typically do. Sus nacadas, his tacky, uncultured behavior, ways of doing things.

Guarro

Guarro covers much the same territory. Es bien guarro. That guy's really low class, de lo más bajo. Another synonym is pelado.