Answer: According to Mercutio, her chariot is an empty hazelnut, made by the squirrel or old worm.
Explanation:
Mercutio is a character from Shakespeare's Romeo and Juliet. He is a friend of Romeo who dies in a fight with Tybalt. He is presented as quite witty and funny.
In Act I, Scene IV, Mercutio tells Romeo about the Queen Mab, who visits people in their dreams. Romeo describes the Queen Mab in detail, explaining that she is a fairy responsible for dreaming. Her chariot, he argues, is an empty hazelnut, which was made by the fairies' coach-makers - the squirrel or old grubworm:
"Her chariot is an empty hazelnut
Made by the joiner squirrel or old grub,
Time out o' mind the fairies' coachmakers."
She uses her chariot every night when she travels through the brains of lovers and makes them dream about love.