A little bird told me

2/3 “A little bird told me“
I studied this idiom today.
This expression is considered old-fashioned in American English.
It is used when a person is trying to hide the source of his information
It indicates that the person knows something that is a secret and wants to withhold the identity of the person who let him know about it
It is a teasing manner of saying that you do not intend to unveil how you know something
＜Example Sentences＞
A little bird told me that you are becoming a Japanese.
噂によると、日本人になるそうだね。
Incidentally, a little bird told me that your birthday's coming up.

I’d like to believe that a little birdie told you about my secret 
but I know exactly who it was that let you in on it.

A little bird told me that it is your wedding anniversary today.
A little bird has told me all about your journey to New York.

Things a Little Bird Told Me Quotes said that
“When you hand good people possibility, they do great things.”
Source: theidioms.com　and so on

Thank you for your comment.
I think you can use both good and bad things.
It is used for saying that you are not going to say who told you something.
A little bird told me means “I found out this information from a source I cannot or will not reveal.”

A little bird told me you got engaged.
A little bird told me you’d got a new job.
A little bird told me that his family is a petticoat government.