He convinces his sister's geek to fuck her

A geek sister is like a wild card: you always know that you have an easily accessible pussy in which you can put your cock in an almost certain way. So if the thing gets twisted with your girlfriend or you have tired of the straws maybe a good option is to do like this guy and see if you convince your sister to put his cock in his mouth, suck it and take a Good dust to enjoy that tight pussy that is usual for these little experienced whores. The slut ends up thanking her brother for penetrating her.