To tell tales is to report somebody's wrongdoing in order to get them into trouble. The offence is in the telling.
It belongs to childhood above all, and a telltale is a child who does it, which is one of the earliest social crimes anybody learns about. Adults keep the disapproval, since nobody likes an informer, even when the report was justified. That tension is genuinely difficult. There is a separate phrase, telling tales out of school, meaning revealing private matters to outsiders.
1phrasetell talesTo report another person's misbehaviour in order to get them punished.
“Nobody likes a child who will tell tales.”
Practised in Idioms, A Man Called Ove
First appears in chapter 5 of A Man Called Ove.
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