Yeah, a friend's mother told me that one about a month ago when trying to make me eat breakfast. (Eating first thing in the morning tends to make me ill.) The cite she gave me was "my aunt, who was a nurse." It didn't sound medically plausible to me.
"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!"