a little bird told (or whispered to) - To be told something by a source that’s so unreliable, it mi

To be told something by a source that’s so unreliable, it might be a kid with a crayon and a rumor.

A little bird told me you’re going to fail the year.

A little bird whispered that your dad's a pirate.

A little bird said your teacher’s a robot, and I believed it.