When radio stations got their hands on another Luger-produced track - “B.M.F. Months later, Luger - who says he was “broke as a joke” by that point, about to become a father for the second time and seriously considering taking a job stocking boxes in a warehouse - heard that same beat on the radio, transformed into a Waka song called “Hard in da Paint.” Before long, he couldn’t get away from it. Waka had asked him for one more beat, one that could potentially be the album’s first single. Luger had recently spent a few months in Atlanta with Waka, sequestered in a basement, producing most of the music for Waka’s debut album. When the track was finished, he e-mailed it to a rapper named Waka Flocka Flame. It had a thunderous canned-orchestra melody, like an endless loop of some bombastic moment from Wagner or Danny Elfman a sternum-rattling bass line and skittering electronic percussion that brought to mind artillery fire. A few years ago, before anyone knew his name, before rap artists from all over the country started hitting him up for music, the rap producer Lex Luger, born Lexus Lewis, now age 20, sat down in his dad’s kitchen in Suffolk, Va., opened a sound-mixing program called Fruity Loops on his laptop and created a new track.