In Spanglish, Chicano, or Mexican American Slang, women who are Mexican American or dark complected that tend to put on a lot of make up to hide the fact that they are Mexican. They tend to over do the lighter complected make up to the point where it looks caked on.
Above that,
Cha Cha's are lower in the hierarchy as Cholas in the
Chicano Gang Culture of Los Angeles, California. Basically, it is a modern
Malinche behavior that betrays his/her own Mesoamerican roots by trying to "cover up" their true identity.
Women that lose sight of what they really look like to the rest of the world and over do it with Make up.
Cha Cha's can be compared to the "Jersey Girl look" from the Bon-Jovi days of the 80's but add to that the fact that she's a Latina who cakes on the make up to look white.
Example:
Jessica Alba is half dutch and
half Mexican, she does not want to be called a Latina and she cakes
on the Make up like a "
Cha Cha" to cover up her dark complexion.