Calling All Shoppers!!

I need help. I'm in a conundrum (is that how you spell that word?). I have two styles that I rely on - my grunge look, which is slicks and running shoes, or my "other look" - which is basically cute jeans, a dressier style shirt, and heels. When we go to the bars, this is what I wear. At work, same thing.

Here's my dilemma. We are tailgating/going to a football game/partying at our house afterwards this weekend. Fine, no biggie, right? Except we have about 20 members of Mr. Who's family coming to join us. Mr. Who has two sisters my age who are super cute and always dressed to the nines. One sister, we'll call her N, I love dearly. The other one, we'll call her P, I have had issues with in the past. She is very competitive and always is trying to "out-do" me. This does not sit well with me. I am always the winner, dammit!!

My point - I need a cute casual/dressy outfit to wear this weekend! Something that will make P realize I will always be the winner. Please, someone find me something cute to wear - that is football appropriate but does NOT entail wearing running shoes. And right now, money is not an object as I have stolen Mr. Who's credit card and will deal with the consequences later.