NASA has allegedly used a Rover as its paintbrush for this interesting form of art according to this Mars picture. The picture was found by individuals from the internet scanning space images.
No matter what NASA's defense is on this image, it's pretty hard to deny the likeness of these tread marks to that of male anatomy. If the report is true, it would suggest that those in NASA could just be a bunch of nerds with an impeccable sense of humor and a childlike attitude at heart. I'm sure there are many men out there who, if given the chance, would do the exact same thing -- it's really a once in a lifetime opportunity.
Either way, the report on this Mars picture is quite hilarious and has amassed quite a bit of attention.