In the Uk the word "sambo" is considered a racially abusive term in the same ways as the "N word".
The Collins Dictionary says: an archaic and taboo word for a Black person.
The Oxford Dictionary says: offensive A black person.
Just saying "Little Black Sambo" in the UK would pretty much guarantee you being fired from your job, and possibly being arrested for violating Anti-Discrimination laws.
I just thought you should know.