In honor of their career milestone, the band released an emotional new track titled "2011" on Dec. 3. "This year we're celebrating 10 years of 5 Seconds of Summer," the group said in a press release.

The rocker is going to be a dad! Check out some of ET's top new music picks of the week! 5SOS reflects on their journey as the band drops its latest single, 'Complete Mess.' Check out some of ET's ...