5SOS Fam, 5 Seconds of Summer's 'Good Girls' music video is finally here -- and yes, it was totally worth the wait.

We're already obsessed with the concept of the vid, which takes place at a reform school for "bad girls." The guys of 5SOS -- looking their wholesome best in vests and ties -- are brought in as a classic strings quartet in the hope that their music will help the ladies to reform.

"A good girl is like sweet lemonade on a hot day," Luke tells the school's headmaster, as the guys burst out into an a cappella rendition of the simile.

"A good girl is when you touch the fret of your cello and you feel the warm embrace," Calum agrees suggestively.

So just what happens when 5 Seconds of Summer get unleashed in the bad girls' reform school? Well, just watch the video above to find out!

See Michael, Ashton + More Celebs' Yearbook Photos!