This picture has been floating around the internet recently:
Is it a genuine picture or photo-shopped? Or perhaps its some sort of optical illusion similar to the wagon wheel effect?
It's an effect of the camera's rolling shutter.
In many cameras, the image sensor doesn't capture the entire scene simultaneously. Instead it samples from its pixels row by row. Objects that move between samples may appear distorted across the image.
Here's a paper that describes the typical rolling shutter sampling process and the resulting image geometry.
This article has a lot more details on the rolling shutter effect. Further down the article, when it mentioned (s=1), shows the effect being captured by the above photo: