We will have none of those kinds of pictures here, but if you would like to check it out follow this link over to Wrestling Classics and the John Cena tweets nude pic (NSFW) thread. You don't actually see his "Little Jimmy" as it were, but it's certainly a NSFW pic. It would appear that the pic was meant to be a Direct Message that was accidently sent out to Twitter at-large.
Cena covered by posting this Tweet some point after it. For that matter he posted this one about his car as well.
I'd be curious to know if there are any consequences for this. Luckily for him the picture isn't as revealing as it could have been. I would love to know if this pops up on WWE's radar at all, honestly.