nail a lie

nail a/the lie

To prove, expose, or demonstrate that something is false. Often used in the phrase "nail the lie that (something is the case)." The model has gone on record numerous times to nail the lie that her photographs had been digitally altered by the magazine. We're working to nail a lie that has continued to be spread for years: that simply giving up carbs will help you permanently lose weight.

nail a lie

BRITISH, JOURNALISM

If you nail a lie, you show that something is definitely not true. Top designer Calvin Klein is one of those helping to finally nail the lie that young is best.

nail a lie

expose something as a falsehood or deception.

The reference here is to shopkeepers nailing forged coins to their shop counter to expose them and put them out of circulation, or to farmers pinning dead vermin to a barn door as a deterrent to others.