Often confused with Capon which is "A castrated domestic cock fattened for eating." -Dictionary.com.
The spelling of "cappon" is a term used to describe a person who is often tormented by others. Typically the persons performing the harassment have the end goal of driving the cappon to the point of insanity and gain simple pleasure out of the cappon's reactions.
Bill is such a cappon. I just can't stop driving him up a wall!