And the truth is finally REVEALED!!!
[Image via Kylie Jenner/Instagram.]
After chatting with host Elvis Duran about their rapidly growing fan base and performing their single, Amnesia, the group paid an AH-Mazing homage to Katy!
We absolutely love Katy, so we think the boys chose the perfect song to cover.
5 Seconds of Summer's self-titled album was released TODAY…so we're sure the group will soon be busy promoting their new songs and touring!