Penectomy game:
Make up you own mind and think of a time controlled penectomy device.
Something that she can easily stop anytime, ... but not from where she is sitting: In 2 meters distance from him, masturbating.
They can both see the time tick away. And he hopes that in the critical moment she will really be ready and willing to stop masturbating and stand up to save his cock.

Girls, if you were right before your orgasm..., wouldn't you?