Mad as the sea and wind, when both contend
Which is the mightier: in his lawless fit,
Behind the arras hearing something stir,
Whips out his rapier, cries, ‘A rat, a rat!’
And, in this brainish apprehension, kills
The unseen good old man.
– William Shakespeare
Hamlet, Act 4, Scene 1. Gertrude says this in response to Claudius who asks how is Hamlet. She tells him that her son is quite mad and has killed Polonius. But Hamlet has already told her that he is not mad, but is pretending to be, and asked her not to reveal this to Claudius. So she tells Claudius a lie.