Simple Creatures is a collaboration between the members of two pop-punk bands, blink-182's Mark Hoppus and All Time Low's Alex Gaskarth. This was the first song they wrote together. It was released as their debut single after it got the thumbs up from close friends.

"In the studio it felt immediately like it was the song that best defined Simple Creatures," Gaskarth told Kerrang. "It's gritty, grimy, rooted in the musicality we both came up on, but with a twist that takes it away from anything we've worked on before."

The track is about being destroyed by the things you love. Gaskarth explained: "'Drug' is a song about someone or something you want the most, being terrible for you… Feels great until it doesn't, but then you can't stop."

Gaskarth considers the song to be a big "middle finger" to those expecting him and Hoppus to come up with a pop-punk sound. Instead they're saying, "We get to do what we want."

"It's just brash and trashy and sultry and gross and sludgy and weird," he said to Alternative Press. "It felt like it married our backgrounds - coming up from pop-punk and punk rock and the mindset of that - with these new trashy sensibilities we were starting to craft. I loved that it felt brash and abrasive. The 'na na's became the cheerleader of the whole group. That choir of 'na na's was our middle finger to what everyone would expect."