Duplo problema

You've just become the step-brother of two super busty twins. However, they couldn't be more different from each other. One twin is obviously incredibly self-centered and slutty, while the other curvy twin is more reclusive and nerdy. You walk in on them one day to discover them in a peculiar mood. The sluttiest twin wants to have a contest. She wants to know which twin you think is the hottest. Not to be outdone by her nerdier and cuter twin, she starts to get a little naughty... And her step-sister follows suit. Next thing you know, your dick is hard, and both of the twins are looking at the bulge in your pants with hunger in their identical eyes. "How about you be a stunt cock? That way I can teach my step-sister how to use one...." The slutty twin says. How could you possibly refuse?