There's no special handshake. No code word. But for one secret group on the University of Washington campus, identification papers are a common denominator. Or rather, a lack of papers.
The University's "Purple Group" is for students who came to the country illegally. They're often called "dreamers." This type of student group has become more common on college campuses in the past decade.
As Liz Jones of Seattle public station KUOW reports, some of these groups remain more hidden than others.