iHeart Media's 107.5 FM WGCI's announced it's line up for their annual Big Jam in Chicago presented by Boost Mobile. The concert is headlined by Chris Brown, Trey Songz and Young Thug. The line up also includes Lil Yachty, Desiigner and Chicago's own Gherbo & Lil Bibby. The event will take place December 30th at the United Center. Tickets are on sale now.