Birthday creampie!! Sry sister.. did I finally go too far??

It was supposed to be a comfortable birthday with the family, I was already getting ready when my sister's friend was at the door and my sis was probably still looking for a parking space! The boyfriend is keen on me, no wonder my sister is always walking around in a sloppy look. Which man gets horny with something like that? So we use the opportunity for a quickie and when he sprays my sis suddenly stands in the room! Oh man, she's really mad if I can get it back?? Did I finally go too far?