From TVGuide.com: This, you're gonna love. But first, here's how it all went down.
At one point during this week's episode of the CW's Supernatural, "Yellow Fever," Dean waits for Sam in the Impala. As Sam approaches, he discovers his bro reclined in the front seat with his eyes closed, air-drumming and lip-synching to Survivor's "Eye of the Tiger."
Jared Padalecki's cue to costar Jensen Ackles was to tap on the roof of the car, interrupting Dean's jam session. But on one take, Jared had this thought: What if I didn't give the cue? What would Jensen do?
Let's just say that "Eye of the Tiger" is one of Jensen's favorite songs. And this video erases any doubt of that. (You can ever hear the crew laughing as Ackles lets loose.)
While this sneak peek will more than entertain you, be prepared to get the entire 90-second version — featuring even more impromptu "choreography" — as a coda to this week's episode.
The sneak preview video can be found here. Just go to the Preview section it is the 3rd video.
ETA: Here is the YouTube Clip!