Sorry there is no description in the Photographer's Comments section. The reason is because I submitted this with literally only a few seconds left, and didn't have enough time to write how I did it. I'm surprised it actually got in.
I came up with the idea about 20 minutes before the challenge deadline, and my battery ran out about 10 minutes later. It's just a long exposure with a remote flash manually triggered twice, with two different expressions. I believe it's unique because the "strobe" effect is only on a small part of the picture, or at least was supposed to be. It was (obviously) quite difficult to sit still enough with my head in exactly the same place while making a different expression. I believe I could've done a MUCH better job if I had more time and more tries. This was the best of the 10-15 I was able to do before time ran out.
Hey, I tried this (hard to get right isn't it) but I wasn't happy with the clarity of my teeth. Same here although much more defined than mine was. Well thought out and meets challenge well. 8
The effect on the mouth area is a bit unsettling and interesting at least, but the consequence of the rest of the face having no sharpness at all (from the incidental movement) is far too big of a problem to be ignored.