This idiom means to tell somebody something that you know to be completely false or untrue. To 'lie through your teeth' is to lie deliberately, without shame. The force of this expression means that to accuse someone of doing so can lead to conflict. That's why you would generally only say it to, or about, a person you are absolutely certain is lying. As the video shows, this expression is common in both a social and professional context and is similar to the phrases 'tell a pack of lies,' 'lie to one's face' and 'a barefaced lie'.

1. Adam told me he wasn't at the party last night, but I know he's lying through his teeth because there are pictures of him there.
2. I had to lie through my teeth to the police so they wouldn't give me a fine. I'm surprised I got away with it.

1. I lied through my teeth in the interview and said that I have a lot more experience than I really do, so I could get the job.
2. Politicians in this country can not be trusted. They are well known for lying through their teeth and making promises they don't keep.