The Chainsmokers looked fresh on the red carpet before their #MonsterMashUp debut in Liverpool. This image appears in the gallery:#MonsterMashUp 2016: ALL The Photos From Last Halloween's BIGGEST Party 64. The Chainsmokers looked fresh on the red carpet before their #MonsterMashUp debut in Liverpool. (Pic: PA) 77 images See the full gallery: #MonsterMashUp 2016: ALL The Photos From Last Halloween's BIGGEST Party