Thanks guys, glad you like it so far.
So, here's a link to a video with the thong slip that I'm looking for - it was in the England-Argentina game at the Champions Trophy last year. The annoying thing with the video is that it glitches at exactly the point of the thong slip (the 38th minute mark).
Basically, the English number 24 Shona McCallin dives in to make a tackle, ends up on the ground and basically has pantsed herself. She flashes a red thong before getting up again. You can see the thong briefly in the video, but there's a picture floating around on the web that perfectly captures the moment. Hope someone can find it!