Every rap DJ and producer who works on mix tapes and Internet-giveaway tracks needs a "drop," a sonic signature that alerts listeners to his or her presence on a song. Drops are essentially in-song advertisements, and a lot of them are prosaic, along the lines of some dude saying a DJ's name in his best tough-guy voice. But some folks have made the drop an art form in and of itself. I could listen to my favorite drop from Atlanta mix-tape DJs Trap-a-Holics—a brutally unhip white-guy radio-announcer voice saying "Damn son, where'd you find this?"—all day. And I love it when the little kid yells "Tony Baines!" at the beginning of a cut by local producer Tony Baines. For one thing, the kid sounds so excited that it's hard not to crack a smile. But that drop also lets me know that I'm about to get hit with one of Baines's typically ebullient beats.