The setting was in Luke 23:
1 Then the whole assembly rose and led him off to Pilate. 2And they began to accuse him, saying, “We have found this man subverting our nation. He opposes payment of taxes to Caesar and claims to be Messiah, a king.”
3 So Pilate asked Jesus, “Are you the king of the Jews?”
“You have said so,” Jesus replied.
Then Pilate sent Jesus to Herod whose intention was to make fun of Jesus:
11 Then Herod and his soldiers ridiculed and mocked him. Dressing him in an elegant robe, they sent him back to Pilate.
As Herod was reluctant to kill John, he was also reluctant to execute Jesus. Herod wouldn't mind, however, that Pilate would execute Jesus for claiming to be the king of the Jews because the title infringed on his title. So he dressed him up like a king sarcastically and sent him back to Pilate. Now it was Pilate's soldiers' turn to continue the mocking in Matthew 27:
27 Then the governor’s soldiers took Jesus into the Praetorium and gathered the whole company of soldiers around him. 28They stripped him and put a scarlet robe on him, 29and then twisted together a crown of thorns and set it on his head. They put a staff in his right hand. Then they knelt in front of him and mocked him. “Hail, king of the Jews!” they said. 30They spit on him, and took the staff and struck him on the head again and again. 31After they had mocked him, they took off the robe and put his own clothes on him. Then they led him away to crucify him.
Herod and his soldiers and Pilate's soldiers intended to mock Jesus. Ironically, Jesus was really the King of the Jews. The final irony in this episode was in John 19:
19 Pilate had a notice prepared and fastened to the cross. It read: JESUS OF NAZARETH, THE KING OF THE JEWS. 20Many of the Jews read this sign, for the place where Jesus was crucified was near the city, and the sign was written in Aramaic, Latin and Greek. 21The chief priests of the Jews protested to Pilate, “Do not write ‘The King of the Jews,’ but that this man claimed to be king of the Jews.”
22 Pilate answered, “What I have written, I have written.”
What did Herod communicate when he sent Jesus back to Pilot in “splendid clothing?”
Jesus was the king of the Jews. Execute him if you want.