In Vietnamese, Coc means toad/frog or june plum ; Cac is male private part.
I've asked my Vietnamese family, and nobody has heard about Coc mango.
I don't know the history of "cac" mango in the US, and I tend to believe that cac is a misspelling of Cat, which means sand. Some people claim that cat mango has a sandy texture when they bite into the flesh, hence the name cat.
I told my family about "cac" mango, and people either were rolling laughing or giving me a WTF look. And, yes I decided to relabel my "Cac" mango.
