A traumatic horrible rape? Let's say they gave Bucky something to induce priapism. At first it functions like sex pollen, and he's hot for it for the first two, three, even four women. But even as the lust abates, the erection doesn't. Instead, he's just helplessly hard, getting tired and miserable, starting to beg for mercy as woman after woman mounts him, and he comes and comes, until he's raw. When it hurts too much to come, that's when they bring out the cattle prod.