DJ Mustard Drops Club-Ready 'FourFiveSeconds' Remix

When super-producer DJ Mustard isn't working on new beats for artists like YG, Big Sean, Jeremih and Fergie – and that represents just a small fraction of what he's currently into – the 24-year-old Los Angeles hitmaker spends his free time crafting unsolicited remixes for big singles like Beyoncé's "7/11" and, as...