Wig Day at work!

You think a creative department needs to be bored in order to invent and celebrate something called "Wig Day"? Pffft! It's pretty darn interesting to see what types of stress-bustin' diversions emerge when overworked, exhausted people decide that a little FUN is in order. Here I am with a few mm readers. In case any of them decide to run for political office one day, I've incorporated the ever-so-functional "rectangles of anonymity." Can you guess which one is "S" and which one is "M"?