Lie through your teeth
Definition 1 of 1
Pro Tip 1/3Strong Denial
Used when someone strongly denies the truth, often in a brazen or shameless manner. 
Even with the evidence in front of him, he lied through his teeth, denying any involvement.
Pro Tip 2/3Emotional Impact
The phrase suggests the speaker is being deceptive with confidence and has an arrogant or bold quality. 
She could lie through her teeth about her qualifications without a hint of nervousness.
Pro Tip 3/3Informal Expression
This idiomatic expression is informal and usually used in spoken language or casual writing. 
During the debate, each candidate accused the other of lying through their teeth.