Sentence:  ... I remember well that one of his jests on this occasion was pinning the wig of His Grace the Lord Archbishop of Canterbury to the wig of that right reverend Father in God, the Lord Bishop of London, as these two holy men sat discussing the question of a pension on the Irish establishment, for one of the King's cast-off mistresses; and when they rose and moved in opposite directions great was their dismay at finding that they <WSD>unwigged</WSD> each other. 
Meaning of the word marked with <WSD> tags:  To remove a wig from.