Something that I find very erotic is slapping the victim throughout their ordeal, especially when he/she is being nailed to the crossbeam. There is something fascinating about the power dynamic between the executioner and the victim where the victim is not even allowed to suffer freely without the threat of more abuse. The same goes for pulling the victims collar while they are carrying the cross, spitting in their faces, groping the victim, kicking them to walk make them walk faster, and so on. Slapping is by far the most erotic, particularly while they are being nailed since you know the victim cannot control their pain response.
An example of slapping occurs in this film (I'm not sure what the name of the film is) at the 10 second mark:
What other disgraces do you find arousing?
An example of slapping occurs in this film (I'm not sure what the name of the film is) at the 10 second mark:
What other disgraces do you find arousing?