Katy Perry is showing off her nerdy side in the video for the single "Last Friday Night (T.G.I.F.)." Braces, headgear and big glasses ... it's all there. The 80's are in full effect!

In the video, Perry goes from dork to 80's glamour goddess, and we're lovin' the neon green skirt. Corey Feldman and Debbie Gibson play Katy's parents and Glee's Darren Criss plays her cool friend. Totally rad!

Find out who else makes an appearance in the wacky video ... after the jump.