The phrase, "Chyea, ma" was originally used by a young bi-racial (African-American and Cambodian) girl in Seattle to say "Yes" to her Cambodian grandmother, who she refers to as "Mom" (ma). While saying this in front of a young African-American female from Tacoma, she realized this was the easiest thing to say and began to address Cambodian's around Seattle as, "Cha ma."
African-American girl: Man, that is so Cha Ma of you to say.
Cambodian girl: I wore socks with my flip-flops to school today.
African American girl: That's some Cha Ma shit.