Calvin and Hobbes by Bill Watterson for March 22, 1993
Transcript:
Calvin: Look at these TV commercials. Each one is a jumble of lightning quick, unrelated images and film techniques. It duplicates the effect of rapidly flipping through channels. It's a barrage of non-linear free association. Hobbes: I guess they're admitting that a 15-second commercial exceeds the American attention span by a good 14 seconds. Calvin: Huh? Are you still talking about that?
It was actually disproven that such advertising had any effect at all, and the messages aren’t technically illegal in the US but can result in the broadcasting company having their license away by the FCC.
http://www.snopes.com/business/hidden/popcorn.asp