You die immediately

Your sister walks downstairs with an erection whose presence makes a joke of what all other cocks have ever expressed. The heat it gives off warps the wood of your fragile home. The sizes its turgid form angrily pulse between proudly reject the human body as recipient. The density of her blood pressure twists the world around her in a bizarre dancing worship of her womanhood, with these fluctuations deafening all other sensation as your whole being is washed away simply by bearing witness to her throbbing spire.

The sum of your identity spun forward pales in comparison to what it would mean to even comprehend how potent and virile her cock is. And your pathetic wriggling form capsizes under the weight if its presence.

Your heart stops. Your mind goes blank. Your form fades.

You lack the strength to even behold to your sister's perfect cock as it destroys all that you hold sacred. If you were a better man it might not be so. But you lack the strength to even see her fuck your girlfriend. Alack alack...

(lol cuck)