Well, the "where to wear it" is "don't bother." It doesn't do anything. Logic would indicate that it's a fairly new piece of folk belief, however, since the safety pin is pretty new, historically speaking.
Originally Posted by Jhalak
"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"
"You can't erase icing."
"I can't believe it doesn't work! I found it on the internet, man!"