Alli Simpson Sips (Fake) Milkshakes on Set of Her "Roll 'Em Up" Music Video

YH is at the Cadillac Jack's diner to catch up with pop starlet Alli Simpson as she shoots her retro-themed music video for her single "Roll 'Em Up", which was written by her brother Cody and Selena Gomez! Alli chats with us about collaborating with Jack & Jack for the project, rocking some fashions for her MUDD campaign, and how this version of the song is a fresh take from Cody and Selena's!