What's wrong with that?

This afternoon Eva Grace's best friend, Chloe, came over to play for a little while. The first thing the two of them do when they are here together is strip down to their panties and play dress up. When they are tired of wearing dresses they spend the rest of the time in their undies! This is typical behavior of both of them! I was in the living room when Emma comes running inside and dramatically tells me "EVa Grace and Chloe are in the front yard in their panties!" So, I go outside and tell them they have to come in, the funny part was that they both looked at me and seriously said, "why?" It didn't even cross their minds that they shouldn't be in the front yard necked! This isn't unusual, they usually play in the fenced in back yard in their panties so they don't understand why the front yard is different.