The Jews are embarrassed by the sign which was written in all the major languages. It declared Jesus to be the King of the Jews. Maybe Pilate wanted to report back to Rome or have reports get back to Rome that he had crucified the so-called King of the Jews. This would have made Caesar happy with him. It could also be that he did it to annoy the Jews. Either way, it continues to honor Christ who is the King of kings and Lord of lords. All men serve the Lord and His purposes, no matter what there motivation is.