Not everybody thats mexican talks that way. I know a lot of people that don't even carry those words in their vocabulary.
Of course there are those that like to fit the stereotype and think they're showing their pride by speaking that way, or maybe they just think they're cute. In reality it paints a picture of ignorance in a lot of peoples eyes because a lot of people also believe they shouldn't have to prove what nationality they are in the way they speak. It's like spelling "Messicans" instead of "MEXICANS" to prove your a black person or to be funny.
I'm not saying speak like a straight up square, but don't point the finger in a direction where you point 3 back at yourself.