Niiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiice!
As for girls crucified on their knees, spread honey all over their thighs and lady parts and then release a colony of red ants.
As for girls cuming while crucified, bind them wrist and ankle on the Saint Andrew's Cross, where gravity will work with their weight to bring the maximum pressure on their crotch. The pain is excruciating and they instinctively pull and push with their muscles to move their crotches away from the pain. But lactic acid eventually kicks in and they sag towards that agony until their muscles have recovered.
They go up and down, up and down, up and down again for what seems an eternity. Eventually, the down part involves something alongside the agony, something which makes going down not so bad.
They supernova into a mighty orgasm that leaves them so depleted that they lose consciousness. When they wake up, down from the cross and resting comfy on a bed, the first words out of their mouths are "Please, PLEASE, put me back up on that cross!!!!!!"