Justin Bieber's ex-bodyguard says the 5-year old video of J.B. telling a joke using the n-word multiple times does NOT make the singer a racist ... just a bad joke-teller.
Kenny Hamilton -- Beiber's bodyguard during his rise to fame -- took to Twitter to defend his former employer ... saying, "We all make jokes about people's size, look, or race. That doesn't mean it's right but comedians make millions of dollars profiting off these jokes."
The ex-bodyguard adds, "If someone is racist or prejudice you would know from a persons actions. Not because of a joke a 15 year old says. Yes he said some bad jokes and I know if he could he would take back what was said."
As we previously reported ... sources connected with Bieber say the singer is "frustrated and sad" about the video being released and will address it publicly.
"As a black man I am telling the world that @justinbieber is not a racist." says Kenny. Adding, "I have known him since he was 12 years old and I know his heart."
For what it's worth, we're told the tweet wasn't done at the behest of Scooter or Justin.
Kenny recently took an executive position at Beats Music -- but is still in regular touch with Biebs.