This sounds like one of the many hispanic old wives tales I have heard through my wife's family. Tickling was one of them,

Babies aren't supposed to see their reflection because it will make them vain

Put a red bracelet on the baby to repel evil spirits

Don't let strangers touch the baby because it will transfer jealousy to the baby

There's so many more, and WAY more not baby based myths that I have learned that could fill this thread.