Crash!
I was browsing YouTube on my lunch break and the pre-roll to the video I was about to watch was a St. Jude's ad. I was of course sucked in the moment I heard "Hey Jude" start to play, so I stuck around to watch the whole video. At around 2:58 I saw a bunch of hands making little triangles in the air. It didn't click immediately but then I realized it was a crowd of women who must be Tri Deltas! It's a very short scene, but thought I would share. It's a very nice video after all!
http://www.youtube.com/watch?v=tUO91nzpuJo