Superbowl drama..help please!!?

okay, so my parents are like super strict and they won't let me out unless my sister comes along (vice versa) and they won't ever let us out more than ONE time a week..and well the crisis here is that...my sis and me have been planning to go over to our friends house so we could watch the superbowl together for like over a week, and we had already asked our parents, and they said yes we could go. So we had been looking forward to this day (superbOwl..gO STEELERS!!) and this morning out of nowhere after my parents picked up me and my sis from our weekly volunteer job he took us to the store to go buy a whole bunch of chips and dip and drinks and food and other stuff..and he kept telling me how excited he was about watching his favorite team (gO STEELERS) with his two daughters and i was like (blank) crappp!!!...did he like forget we told him we wanted to go out...OMG is he like in denial??..because i'd hate to tell him we want to go with our friends instead of with him! And our friend paid his mom 40 dollars for foo and chips and he had been lookin forward to today too...idk who to tell..and what to tell them..i'm so confused and i'm stressing out!!..PLEASE HELP!!!!!