We didn't think 'Glee' could get any cooler ... That is, until Keenan Cahill got involved. The famous YouTube lip-syncer caught up with a few faves from the 'Glee' crew recently, and together, they filmed an impromptu mouthed performance of Katy Perry's 'Last Friday Night.'

With Keenan at the front of the stage of this backstage video shoot, Gleeks Harry Shum Jr. (Mike Chang), Darren Criss (Blaine), Dianna Agron (Quinn) and Jenna Ushkowitz (Tina) had no choice but to dance themselves into a frenzy. Each cast member got a moment to show off some sweet, signature moves, before they all appeared on screen to shake their groove things.

Throw in a little Katy Perry and you've got yourself a full-on dance party. It doesn't get any better than this, folks. As popular as 'Glee' is, this foursome should be thanking their lucky stars they got the chance to work with Cahill -- a star in his own right. Not only has the short-stack success story lip-synced along to songs by everyone from Rihanna to Willow and the Black Eyed Peas, but he recently starred in Sara Bareilles' 'Uncharted' video alongside music celebs Adam Levine, Pharrell and Josh Groban.

Watch Keenan Cahill and the 'Glee' Cast Lip-Sync Katy Perry's 'Last Friday Night'