Bement Lab Spirit Week, which started back in 1998, is held once a year, usually in late summer or early fall. Each day of Spirit Week has a different theme, and everyone in the lab has to dress according to the theme. In addition, everyone has to keep in costume as long as they are on campus, even if this means attending a meeting of some kind dressed as, say, Jed Clampett.
The themes are chosen by vote from a list generated over the course of the year. There is no particular rhyme or reason to the theme choices, which typically range from the awfully-inane to the almost-inspired. When appropriate, theme-linked playlists are generated. Friday of Spirit Week is reserved for the theme that gets the most votes and is usually accompanied by a lab lunch and movie. Examples of different spirit week days from the past 12 years are shown below.