Well-Tempered Clavicle (Xanth, Bk. 30)

When a walking skeleton named Picka Bones happens upon a trio of melodic pets and a lovely, lovelorn princess, his dull and passionless existence is suddenly filled with danger, excitement, and the temptations of the flesh. For a plague of appalling puns has been unleashed on Xanth, and only Picka's musical gifts have the power to save the enchanted realm from the dire monster who imperils it.