Comic Book Gimmicks, Urban Legends...
Grant, I THINK that you were part of a conversation when DEATH OF SUPERMAN came out, discussing starting a rumor that most of the black bagged editions contained some cheap remaindered comic book on the basis that nobody was ever going to open it, anyway. It would have been fun, because in order for a collector to check the veracity of the rumor, he would have to actually open the bag, which would "destroy" its value (Schrodinger's Comic?).
I've tried to start a couple of urban legends. One of them that almost worked was a realistic looking FDA warning that it was discovered that vasectomies could possibly cause sterility in men (the punchline was, "It has not been determined yet how vasectomies affect women, but we recommend that any woman who has had a vasectomy should see her physician to ensure that there have been no complications.")
I used to tell smokers they should smoke the filters first because that's where all the vitamins are. If they were stoned enough, they'd believe me...