I just heard about this recently. For anyone else out there who hasn't heard of it, this is what it is. During the service, someone randomly crosses him/herself to see if the people around you will follow. If they do, and then the people next to them do also, you have a "Crossing Wave" going.
I was a little surprised that someone would be irreverant enough to play games like this during Divine Liturgy. It did make me more aware of doing what I was doing, since I have a habit of following the lead of this one guy, who seems to be so confident.
I'm wondering, just how common is this? Am I the only one who hadn't heard of it? Or is this just some isolated game with those heretics up in Seattle? (love you Zebu!)