Geoff:

Here is the passage:

Apocalypse of Peter 81:7-23:
"I [Peter] said, “What am I seeing, O Lord? Is it you yourself whom they take? And are you holding on to me? Who is this one above the cross, who is glad and laughing? And is it another person whose feet and hands they are hammering?” The Savior said to me, “He whom you see above the cross, glad and laughing, is the living Jesus. But he into whose hands and feet they are driving the nails is his physical part, which is the substitute. They are putting to shame that which is his likeness.”

In this text, Jesus declares that at his death it was only the material holder of Jesus that died. Jesus's spirit had departed beforehand. The laughing Jesus is an indication that misunderstanding has taken place. So Jesus is laughing because they thought they had crucified him, but he did not suffer at all, having departed.

dlb