Calum Hood is the bass guitarist and backing vocalist for the pop-punk band 5 Seconds of Summer (5SOS). He met band members Luke Hemmings, Michael Clifford, and Ashton Irwin while attending high school in Sydney, Australia. They began posting cover songs on YouTube which gained popularity. One Direction's Louis Tomlinson tweeted in their support which increased their fan base. 5SOS was then asked to join One Direction on their worldwide tour which launched their career.