When Warner Brothers first released Rebel Without A Cause, they were concerned that kids would mimic James Dean's character and wind up driving off cliffs.
To distance themselves ahead of time from copycat incidents, Warner Brothers had Dean film this public service announcement urging kids to "Take it easy driving out there. The life you save might be mine."
Sadly, the clip was never used because Dean was killed in his speeding Porsche shortly before the movie was released.
Unrepentantly stolen from The Consumerist . Thanks for the heads-up!