Had we known her, Katy Perry would have, like, totally been our best friend back in the '80s. On the cover for her 'Last Friday Night (T.G.I.F.)' single, the 'Teenage Dream' singer shows off both her nerdy side and glammed up, big-haired style.

'Last Friday Night (T.G.I.F.)' will be the fifth single from Katy P.'s album; and unlike her last hit, 'E.T.' -- which shot us into the future -- this one is a blast from the past, channeling John Hughes' 'Sixteen Candles' flick.

See how Dorky Perry is dreamily scribbling in her diary, undoubtedly home on a Friday night wishing to be out on the town with the high school jock? Then, on the flip-side, she's rocking those two-tone triangle earrings with a big smile on her blushed-up face -- braces and all. Boy-oh-boy how we wish this were a true depiction of a teenage Perry-Brand!

The 'I Kissed a Girl' superstar should be careful, though, because a single cover this rad could potentially overshadow the song beneath it. We're sure she won't have a problem, considering the success of the four huge hits that preceded 'Last Friday Night (T.G.I.F.).' Oh, and don't forget those remixes!

Flip on your boombox and catch the latest on the airwaves -- it is impacting radio now.

Watch the 'Sixteen Candles' Trailer