The A-mfggh-C's of Ventriloquism

From Monkey Island wiki

The A-mfggh-C's of Ventriloquism is a book that teaches the art of throwing one's voice. Guybrush can find it in The Curse of Monkey Island by using the magic wand on its companion top hat in the Long John Silver Center for the Performing Arts in Puerto Pollo. He can use the book on many characters, creating awkward or hilarious situations. It is most useful when used on Captain LeChimp, as Guybrush can use the captain's authority to have his first mate Mr. Fossey release the Pirates of Danjer Cove from service, allowing Guybrush to take their ship and the map to find Elaine.