lie through your teeth
US /laɪ θruː jʊər tiːθ/
UK /laɪ θruː jʊər tiːθ/
1.
to tell someone something that you know is not true, often in a blatant or unashamed way
:
•
He was lying through his teeth when he said he didn't know anything about the missing money.
•
You don't have to lie through your teeth to impress me.