There's something about rapping with a spanish accent that is so so so satifying; as in, rapping in english with a Spanish accent and throwing in the odd spanish word. Hmmm, maybe it's because i'm half-brazilian and feel some sort of innate connection to Latin America. More than likely it's because I listened to a LOT of Cypress Hill when I was a teenager (their main MC, B-Real, is half-mexican)
Wikipedia puts it quite nicely when it says that "Chicano Rap is a subgenre of hip hop music... that embodies aspects of West Coast and Southwest Mexican American (Chicano) culture and is typically performed by American rappers and musicians of Mexican descent". The 'culture' of which they speak also refers to the music sampled by the artists; Mexican melodies and Mariachi bands. Exactly the kind of stuff you want to hear with a hip-hop beat basically.
The ultimate chicano rap song has to be 'Tres Delinquentes' by Delinquent Habits. It samples a famous mexican melody 'The Lonely Bull', in particular the recording by lounge-music maestro and king of kitsch Herb Alpert. Anyway, the song is a straight BANGER: