Chicago Bar Phantom Photograph

"My husband and I traveled to Chicago to see my sister graduate from college," says Brittany. "The night of graduation, we took her and her boyfriend out for some celebratory drinks. We spent most of the night in what I understand to be an old building, at a champagne bar called Pops For Champagne. In the photo, my husband and my sister's boyfriend were posing for a picture. We were all seated, there were no mirrors or glass of any kind near us. Lots of people were walking past our table, but when we reviewed our photos on the ride home, we could not get over what the figure behind the two boys. Why is it see-through when even the scenery behind it is opaque? If it was a person walking quickly, why is it transparent and not blurry? And what the heck kind of outfit is it wearing? It looks like a space suit."

This is a very curious photo indeed and I've had a hard time trying to figure it out. But let's take it point by point:

* The photo was obviously taken with a flash since the two fellows are brightly lit. We can even see the hard shadow of the guy with the glasses on the phantom in the background.
* The fact that the phantom caught the shadow indicates that it was really there -- a physcial object.
* We can even see a reflection of the yellowish phantom in the glass being held by the guy with the glasses, again indicating that it's really there.
* So why is the phantom figure transparent? A flash should have captured even a moving object still in the split second the light flashed and the camera shutter clicked. But in some cases, if the flash and shutter are slightly out of sync (which they could be for objects in the background, because the camera is focused on the guys in the foreground), those moving objects can get the transparent look seen here. In fact, if you zoom in on the guy in the black jacket seated at the bar, you can see that his head is blurred from movement and that his face is somewhat transparent. So this camera-flash anomaly can result in some apparent transparency, but I think the phantom object must have been moving pretty quickly to yield this amount of transparency.

So, yes, the photographic anomaly could have caused the transparency on the object, but we still have the question: What the heck is that thing!? I can make out the arms and bend in the elbows, but where's its head? And what is it wearing? It seems to be a one-piece outfit of some kind. To me, that's the most baffling aspect of this photo.

Any other ideas out there?