Ulp. South African ladies Bite Back. With special downstairs teeth. And I quote:

It had been designed with engineers, gynaecologists, psychologists and urologists. It was “hygienic – no human hands will be involved in the manufacture”. In the event of rape, the device folds itself around the rapist’s penis, attaching to the skin with microscopic hooks. It is only when the rapist withdraws that he will realise the device is clamped around his penis.