Thursday

According to The Hitchhiker's Guide to the Galaxy, the Earth is destroyed on a Thursday, and the only survivor from Earth on the day of destruction is a one Arthur Dent, who happens to be wearing a dressing gown. Towels are the most useful thing a hitchhiker can have. Bathrobes are like dressing gowns made out of towels. Hence, each Thursday, CTYers wear bathrobes all day. Or towels if one doesn't possess one. Also, many CTYers refer to the last Friday of camp as Thursday since the world and CTY both end. At LAN the last two days of camp are switched (Friday, then Thursday) so that, not only does CTY end on the end of the world, but one also need not wear a bathrobe/carry a towel to the last dance (which is on "Friday", seeing as you can't have a dance on Thursday).