This has happened to me in the past. Not bad pictures, but I have accidentally sent a twitter message that was meant as a DM. Often it happens when you are posting from the cell phone and forget to type D at the front of the message and just reply instead.
On Twitter this has exploded under the term #weinergate.
The crotch picture can be viewed here. And more pictures have been released of him shirtless and worse, reported by Andrew Breitbart.
Breitbart has been the main journalist exposing Weiner's lies and coverup.