My first thought when reading roxy's post was to say "secrecy." I think that is a generic, general speculation that is in no way negative. We all know we have our secrets. If we didn't, we'd all be one sorority or fraternity.
I would rather have people ask, speculate, and make jokes about it than not notice these things at all. What's the worst that can happen? More negative stereotypes against Greeks...well, for every one that dies, a new one pops us. That's just the way it is. I noticed that no one on here is saying specifics, so we have to be ready for speculations.
Good intelligent question, roxy!
On the whole secrecy/speculation thing....a lot of sororities sign theircorrepsondence/signs/whatever different ways. For example, the Zetas on our campus sign L.I.Z. for "Love in Zeta." Well, Kappa Deltas sign most of our correspondence that is public and private as "A.O.T." I cannot tell you the amount of crazy things that people think that it stands for. It's kind of fun because only we know the secret.