In Shakespeare's A Midsummer Night's Dream, perception is central to the humor of the play.
When Puck puts the "love juice" on Titania's eyes, she perceives that Bottom (the weaver—a human!) is the most beautiful creature she has ever seen (even though he has the head of a donkey), and she falls deeply in love with him—all because of the power of the love potion:
So is mine eye enthralled to thy shape;
And thy fair virtue's force perforce doth move me,
On the first view to say, to swear, I love thee. (III.i.131-133)
Puck and Oberon feel this is the height of entertainment—that the queen of the fairies should fall in love with a human with the head of an "ass."
Under the spell, Demetrius and Lysander both perceive that they love Helena. In fact, they fight over her. Helena believes that she is the butt of a joke between them, and scolds both men.
O spite! O hell! I see you all are bent
To set against me for your merriment.
If you were civil and knew courtesy,
You would not do me thus much injury. (III.ii.147-150)
Although magic is at the heart of the misperceptions of the play, it is these misperceptions that create a great deal of the humor, not just where Titania is concerned, but more so with the lovers. To start, neither man loves Helena; after they are enchanted they both love her, and neither man loves Hermia. It is not until Oberon steps in, that all is set to rights. The perceptions of what should be and what the players come to believe as real, make for a great deal of confusion and entertainment for the audience.