I voted for "I have a work issued uniform or similar, and change there", although we don't have uniforms, we have a dress code
I keep my work shoes under my desk, an extra pair of socks and a pair of pants in my file drawer (no files

), an extra blouse, and a couple of sweaters. I normally put a shirt in my messenger bag every morning, and bring a set of pants every other day, or according to my needs. I go through about 2-3 pairs of pants a week (2 black dickies, and brown cordoroy (sp??)), five shirts a week, and 1-3 sweaters a week. I usually wear collared shirts, and sometimes throw on a v-neck sweater so's I can flash the collar, yo.
I'd rather be naked, tho...