let it slide

1.

Meaning: that you are not going to bother worrying about something; that you are not going to bother to chastise a person for something

Example of a father speaking to his child: "Vilma, your grades have been poor this quarter, but I am going to let it slide, and not tell your mother about it."

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— Vivi
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see
[проехали]
[забить]
Cf.
[give loose reign to sth/sb]