Supernatural: 10 Biggest Fan-Service Moments

10. Eye Of The Tiger

This one's a bit of a cheat, because it doesn't technically take place within a Supernatural episode, but rather after one. You see, at the end of the sixth episode of Season Four, Yellow Fever, viewers were treated to a bit of a bonus outtake before the credits rolled. While at first it would appear that it's business as usual, with the Executive Producers credits appearing onscreen, it quickly becomes apparent that something is different this time.

The distinctive opening notes of Eye of the Tiger begin to play, accompanied by a shot of the Impala, with Dean's fist rising up from beneath the windscreen, pumping to the beat of the song. This is followed by a title card that reads "Supernatural presents Jensen Ackles", leading to about a minute of unscripted awesomeness as Ackles raises up from the Impala's front seat and begins to lip-sync to the iconic power ballad.

Ackles puts his all into the performance, climbing out through the window and up onto the Impala's roof, busting out moves all the way, including an iconic bit of leg guitar - all the while the cast and crew can be heard laughing, before they break into rapturous applause at the end as Ackles holds his hands high and dismounts from the car victoriously.

The production team clearly knew that fans would get a kick out of Ackles' impromptu performance, so they threw the clip in as a little treat. For that, they are no doubt eternally grateful.