how did the ghost assert his dignity in the Canterville chase?

The Canterville ghost was constantly humiliated by the twins, who played tricks on him. The humiliation he faced whilst he was dressed as "Black Isaac, or the Huntsman of Hogley Woods," angered him and he planned to make one final effort, to assert his dignity. He planned to visit the twins, dressed as ​"Reckless Rupert, or the Headless Earl." He felt that this was his most successful disguise, and he visited the twins' bedroom that night. But when he flung the bedroom door open, a jug of water fell on him and made him wet. The shock of the incident was so great that the ghost suffered from a severe cold the next day.