A few weeks ago, JUSTIN BIEBER hung up on a radio interview after the host told him his song "Boyfriend" sounded like JUSTIN TIMBERLAKE

--He meant it in a good way . . . Bieber took it in a bad way.  Quote, "Man, that's crazy, because our voices sound nothing alike . . . saying I sound like someone else is not really a compliment."

 --Well . . . maybe THIS will sway him?  A DJ named Raheem D created a mashup of Bieber's "Boyfriend" with NSYNC'S old song "Girlfriend".

--And it's SO seamless it actually sounds like one song . . . where Bieber and Timberlake DO sound VERY SIMILAR.  Oh . . . and the songs themselves sound surprisingly similar too.