CALIBAN: As I told thee before, I am subject to a tyrant, a sorcerer, that by his cunning hath cheated me of the island.
ARIEL [invisible]: Thou liest.
CALIBAN [to Trinculo]: Thou liest, thou jesting monkey, thou! I would my valiant master would destroy thee! I do not lie.
– William Shakespeare
The Tempest, Act 3, Scene 2. As Caliban recounts the situation on the island to Stephano and Trunculo and tells them how he is subject to the tyrant Prospero, Ariel has a little bit of fun at their expense. The spirit enters, invisible to the other characters, and starts to make trouble for them by impersonating Trinculo with his voice.