Craig Campbell -- I Made 'Royals' Mine ... and I'm Gonna Crush More Pop Songs

Lorde was just the start for Craig Campbell -- the dude who turned "Royals" into a country hit ... because he says he's fixin' to slap some twang on a slew of other pop songs.

We got Craig leaving Losers bar in Nashville where he explained how a good ol' boy from Georgia ends up singing a New Zealand teenager's song.

Hint: It's all about that southern accent.

Watch the clip ... Craig also tells us he's going back to the well -- cranking out a medley of songs from different genres.

He's looking at you, Justin Bieber.