I attended school in the midwest and our chapter snapped all the time. I guess I assumed most chapters did this. It might seem strange to people who never did this in their chapter, but I will say that it came in handy when it was 2 am at an MS session and we were all tired and crabby and not that articulate anymore.
When I went on to grad school in the same area, many of my classmates were GLO alums. I recall one particular day in lecture, someone made a remark many of us agreed with, and a classmate who was a Psi U said, "Ok!!" and started snapping (he was one of these really outgoing, assertive types), and about
3/4 of the class started snapping with him. It was almost instinctive for most of us to show agreement this way. Only when I looked around at the non-Greeks in the room did I realize, oops-they have no flipping idea what we are doing or why.
I had to explain it to a few of my friends after lecture.