In my senior year at UC Berkeley, when I was trying to pull double duty by attending classes and working in the Silicon Valley, it was common that I'd show up to lectures or class discussions in a button down shirt and slacks, while the rest of my classmates were the definition of casual. I had mentally moved on beyond graduation, and so had the wardrobe.
Since graduation, I've tried to appear professional, sometimes to belie my youth - in an attempt to be taken seriously, and have consistently dressed the part. In fact, in the summer of 2001, when I asked for a week off from work, I was told by my boss that he wouldn't sign the vacation slip unless I showed him a store receipt proving that I had purchased at least one pair of shorts. Truth was, I didn't have any until I met his demands.
As a result, today's incursion into jeans and sneakers land raised quite a number of eyebrows around the office, as did the fact I hadn't shaved, and showed up slightly scruffy. Many made comments - one saying he confused me for one of the engineers, while another, with a smirk, thanked me for "dressing up." Amusingly, even in my dressed-down state, there were others in shorts and sandals, or t-shirts in various stages of wear and tear. But because I had broken with what they expected, I was the subject of discussion.
At some level, this is a good thing, as I've forged a personal brand that includes the professional business look. While it was fun to make a one-day break from this, even if just to see the reactions, but I don't anticipate it happening on a more-regular basis in the future. The Tommy Bahama shirts and kakhis quota can be consumed by the rest of more casual corporate America.