1º_ It is the feminine of chamo, in its meanings of "boy, youth" and also "friend, companion". 2º_ The dirty rag can also come from a masculine meaning to call stray dogs, which are usually dirty and used by comparison. 3º_ Chama is also the name of some geographical places, such as localities in Zambia or the USA, rivers in the USA and Venezuela, or mountain ranges in Guatemala.
For me meaning of Chama comes from the colloquial word girl boy or young or young girl, but the one who invented that it is dirty dog or coleto rag is not true, it is poorly founded has no basis, this meaning is correctly defined by the royal academy of Spanish language. She doesn't say where she got it from.
In Venezuela means girl, girl, girl, young girl, teen. Female chamo. In Bolivia you mean person of bad taste. In Argentina it means drug, narcotic, marijuana. It is the name of a river in Venezuela and another in the United States. Name of a U.S. people in the State of New Mexico. It is also the name of an African people, in Zambia.