The most pervasive I can think of is that oysters make one amorous. I have no idea if it’s true but it’s been purported for a long time. What others have you heard of? Most everyone knows that green M & Ms make you horny and, IIRC the red ones can kill you. A couple more I remember:
Dr. Pepper is made from prune juice
Maraschino cherries are made of balogna (no word what the balogna was made of)
Pop rocks, if eaten with soda pop will explode in your mouth
If you swallow watermelon seeds, a watermelon plant will grow in your stomach.
You must wait 60 minutes and not a nanosecond less after eating before swimming, or else you will sink like a rock and drown.
I always heard you would get a cramp. Either way, you’re dead.
I haven’t heard it in a long time, but there were some in my grandparents’ generation who believed swallowing chewing gum would lead to appendicitis.
I remember the first time my cousins and I went in the pool after only (gasp!) 59 minutes. We felt like such rebels.
The version I always heard was that it would stay in your stomach for 7 years.
Oh, and if you hold a buttercup under your chin and it makes a little yellow spot, it means you like butter.
I don’t know how many people have told me that swallowing chewing gum will make it permanently lodge in one’s intestines, because it’s “indigestible.” :rolleyes: (Ninja’d because I walked away from my post! I guess this is a big one.)
Eating raw dough will give you worms. Ok, it may not be the smartest thing to eat, but I’m pretty sure worms aren’t a big risk factor.
The “rules” have changed over and over about introducing certain foods into a baby’s diet, sometimes due to allergen concerns. But people tend to insist you do what their doctor/baby manual said back in 1979. An example: my mother was forever trying to get me to put rice cereal in formula bottles for mine so they would “sleep better.” (My kids wouldn’t even take a bottle, but that was a separate issue…)
Swallowed chewing gum takes 7 years to digest.
Special foods (like juice) “cleanse” the body of “toxins.”
Gum would stay in you stomach forever because you can’t break it down.
I heard that one too.
They explode in your stomach and kill you, which is what happened to Mikey from the Life cereal commercials.
How did Mikey get Pop Rocks in Vietnam? 
My first mother-in-law (hey, I have a collection) used to say that “pepper never leaves your system.” I was putting some black pepper on a baked potato or something. I just smiled and said I must be 10% pepper by now.
Although she is the only person I ever heard this comment from I can see that she wasn’t the only one.
http://www.worldshealthiestfoods.net/genpage.php?dbid=205&tname=dailytip
Ooh, just remembered another gem from Mom (a nurse, BTW). Milk is a solid, not a liquid, so you have to drink a lot of other fluids so you don’t get dehydrated. Maybe that was just her, though. I tried to explain the concept of milk solids in suspension/emulsion in water, but I might as well have been explaining how space shuttles launch.
Maybe I got it confused with the 50 lbs of fatty plaque coating everyone’s intestines.
Eating asparagus enhances one’s sense of smell…but only in the bathroom
When did Mikey go to Vietnam? He was 3 when the commercial was filmed in 1972. I think you’re confusing Mikey & the Beaver.
That probably has to do with the old Red Dye #2 controversy. After the dye was banned, red M&Ms disappeared completely for nearly two decades before making their triumphant return.
Have not heard “made from”, but it sure as hell tastes like carbonated prune juice.
Apparently, if I use part of an onion, then put the other half in the refrigerator, it will become highly poisonous.
I must be truly blessed that my family has somehow escaped this almost certain death the last 837 times we’ve done this.
It’s that 838th time that gets you. Or 839, I never can remember which.
The cardboard box is more nutritious than the sugary junk cereal inside it.
A tooth left in (whatever brand of soda Mom didn’t want you drinking) overnight would dissolve.