Karrueche Tran: Lil' Tran Bares Her Butt Cheeks

Karrueche Tran pulled off sexy Lil' Kim ... maybe better than the Queen Bee herself could do it these days.

Karrueche threw a Halloween party Thursday night in Hollywood and nailed the hip-hop legend's look from the "Crush On You" music vid ... just with more ass cheek than Kim.

Blue is definitely not Chris Brown's favorite color, but even he'd applaud this costume.