A 14-year-old girl named Michaela Wallace is apparently trying to win JUSTIN BIEBER'S affection by releasing her own song on YouTube.  It's called "Justin Bieber's Girlfriend" . . . and admittedly it's pretty catchy.  The lyrics include the line, quote, "18,000 other girls here, but he'll be lookin' at me.  I'll hold up a homemade sign, 'Will you marry me?'"  And the chorus goes like this:  Quote, "Gonna be Justin Bieber's girlfriend tonight, and we're gonna be dancin' in the moonlight.  He'll play my song, then it's love at first sight . . . gonna be Justin Bieber's girlfriend tonight."