So, what do you wear when it's 90?

We took Miette to the Brookfield Zoo yesterday, my wife and I and her aunts on my side. It was a blast. It was also about 60 degrees and sunny. Many people were in shorts and tees. More than a few were in sleeveless shirts and what we used to call coochie-cutters. This is less clothing than most people would wear when it's 90 out. What gives? I can hide those choices in people's own stupidity by and large, but as we were walking in at 10 in the morning, we saw a little girl of no more than 5 in a t-shirt and running shorts with her family. Seriously, where are people's heads?
It's always an event downtown, too, the first "nice" day. You'll see people (young women especially) in the stupidest outfits acting like it's 100 degrees out.