As a kid, there were several rumors i unquestionably believed:
1) I was told there was this one kid who blew off his face with fireworks and now lived secluded in the bedroom above his garage. I know he lived there because my friend pointed it out. I was also accussed of being a friend of the kid-without-a-face - but my real friends helped quash THAT rumor.
2) At day camp, there was an abandoned, fenced-off shed way back at the far edges of the property. Rumor had it that an evil guy lived there - and he had captured a kid who had come too close. Of course, I turned down the dare to hop the fence and inspect the shed.
3) My friend across the street swore that if you cut the skin between your fingers you would die. Needless to say, I was very careful.
4) Without a doubt, my older cousins had the entire Major Matt Mason action figure (an astronaut figure that was my favorite toy for a time) set, including all the cool accessories, the other action figures in the series, and the space station playset. Not only did they have all this, but they were hiding it right this second behind the locked door to my aunt and uncle's bedroom and they were NOT going to let me see it.