Ok, you want to know where I think that whole pose originates from? My first girlfriend was a model, and she taught me that when you pose for a close-up (obviously this doesn't work if your mouth is open or whatever), if you bite the sides of your mouth, kind of clamp them in your teeth, it kind of emphasizes your cheekbones.
Try it, it feels like you're doing a really puckered face, but if you feel the side of your face, you aren't. It's quite subtle. But I'd hazard a guess that this somehow got distorted into some dickhead pose.