old wives' tale

Its government said that there were "no border violations by Mi-8 and Mi-24 helicopters", and described the accusation as an "old wives' tale".

No one's spitting in your dish; that's an old wives' tale.

Then I read a trick that sounded like it had to be an old wives' tale: Stick a piece of bread in your mouth.

It is where we get the notion of the old wives' tale.

Another popular old wives' tale is that a full Moon causes women to go into labour.