I'm gonna call chop on that one. I know I don't have a million posts here, but I do have a degree in Industrial and Graphic Design with a solid 15 years in Photoshop experience for both personal and professional purposes.
Here's why I believe it to be fake:
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The head shows signs of the clone stamp being used in order to widen it. You can see the redundant pixels creating a horizontal line through the center if you look closely.
The shaft is pretty obviously mirrored. I, for one, have never seen a penis that is so symmetrical. I'm not gay, so I haven't seen as many as some folks, but this this would truly be a freak of nature.
the left side of the shaft is the most obviously chopped portion to me. I know what he was trying to do. He attempted to add some of the colors in the label on the bottle in order mimic the reflected light that the bottle and label would cast off. Unfortunately, he failed. The layer in which he applied the blue color that mimics the label is either too opaque and/or he didn't use the proper layer transparency setting in order to preserve the shadows on the edge of the shaft on the layer below. This is what gives the left side of the shaft a washed out look, with little contrast and the look of being lit from all around.
It's also a tiny, low res pic, which helps hide Photoshop imperfections really well.
Take it as you will, but I'd wager a significant amount on it being a re-touched image.