The largest eastern diamondbacks on record are 8 footers, so it wouldn't be a stretch to think this is a real photo. However, that would mean the kid in the photo would have to be less than 5-feet tall.
Both pictures in this thread are real, but the lengths are exaggerated. It's a forced perspective camera trick. Holding anything closer to the camera lens than other objects in the frame will produce similar results. It's a trick commonly used on RealJock with cock shots.
The actual length of that snake appears to be just over 5-feet, which would be more appropriate given the 18-21 rattles I'm counting on the snake's tail.