As Jesus is nailed up onto the cross, they are still mocking him. While he suffers, they throw insults. While he dies they taunt him. They didn't understand the gravity of what Jesus was doing, and they didn't understand how accurate their "insults" were.
Mark 15:21 - 15:32
21 And they compelled a passerby, Simon of Cyrene, who was coming in from the country, the father of Alexander and Rufus, to carry his cross. 22 And they brought him to the place called Golgotha (which means Place of a Skull). 23 And they offered him wine mixed with myrrh, but he did not take it. 24 And they crucified him and divided his garments among them, casting lots for them, to decide what each should take. 25 And it was the third hour when they crucified him. 26 And the inscription of the charge against him read, “The King of the Jews.” 27 And with him they crucified two robbers, one on his right and one on his left. 29 And those who passed by derided him, wagging their heads and saying, “Aha! You who would destroy the temple and rebuild it in three days, 30 save yourself, and come down from the cross!” 31 So also the chief priests with the scribes mocked him to one another, saying, “He saved others; he cannot save himself. 32 Let the Christ, the King of Israel, come down now from the cross that we may see and believe.” Those who were crucified with him also reviled him.