Get our free mobile appChristine Manika (TSM) Christine Manika (TSM) loading...Who's Headlining Lallycooler Summer Music Festival in Sioux Falls? Darius Rucker and Jason Derulo will be the epic headliners at this year's Lallycooler Summer Music Festival. Getty Images, Canva Getty Images, Canva loading... Getty Images (Danielle Del Valle) Getty Images (Danielle Del Valle) loading... Lallycooler Music Festival (with permission) Lallycooler Music Festival (with permission) loading...