Boy band 5 Seconds Of Summer have unleashed the promo video for their new single Good Girls.

The perky punk-poppers pose as a "string quartet" in the intro to the video, discussing the concept of "good girls" with a reform school headmaster.

Luke Hemmings says: "A good girl is like sweet lemonade on a hot day."

While Calum Hood oddly compares a good girl to the "embrace" of his cello's neck.

And the teacher introduces the song's chorus when he tells them: "Good girls are bad girls who haven't been caught."

The song proper then kicks in, alternating between the boys performing on an outdoor stage and scenes of increasing disorder in the "school" - which appears more like a prison to us.

Enjoy.