How Many Times Do I Have To Tell You?!?!?!

Am I the only mom out there who has to REPEATEDLY remind her kids of the rules of the house?? Lately around here it's been
Me - "Do we bring food downstairs??"
Usually one of the girls - "No"
Me - "Then why did you bring crackers, yogurt, raisins, drink boxes, ICE CREAM?!?! downstairs??
Girl - "Sorry mommy, it was Maren/Lauren (blame each other) that brought it down.

For Christmas Santa brought our boys a voice recorder thing that can then speed up or slow down your voice. Here's things I'd record on it to be repeated throughout the day:

"We don't bring food downstairs!!!"
"Lift the seat when you pee!!!"
"Make your bed!!"
"When you practice the piano you're supposed to do more than just SIT on the piano bench!!"
"The couches are NOT a playground!!"

Anyway, the list goes on. My problem is, why is it that they don't get it through their heads??? I feel like I'm a pretty stern mom, I don't let my kids walk all over me. I'm very clear as to the rules in our house. What's the deal?!?!

Sometimes I want to just give up and let our house go to pot, don't empty the garbage, tidy rooms, do laundry etc. I wonder though....how long it would take the natives to even notice a difference??