What's the craziest thing you were told by your friends as a child?

Nothing serious, this is for fun. My example was a friend told me you get computer viruses if you use disks that were dropped on the ground outside. His logic was he was told you get sick if you eat stuff off the ground. Sickness is caused by viruses. Computers can get viruses. Computers "eat" floppy disks. So if you put a dirty floppy into a computer you will make it sick by giving it a virus.

Yes it's mostly wrong but you can sorta see the logic...