All of the antics may make more sense when you learn that Wednesday was Caltech's "Senior Ditch Day." The tradition dates back to the school's early days, when seniors would skip class and the underclassmen would sabotage their dorm rooms. Today, it has devolved into a day of strange riddles and tasks.
It seems the definition of "Ditch Day" was somehow lost, since most students were still on campus. But these seniors certainly haven't forgotten how to have a good time.