Update: Added a link to Stealthybox for screencapping the original Tweet.
Gearbox employee Anthony Burch just posted of a man on Twitter, whom he remarked is sleeping like a "lil angel", but what's more interesting than the man sleeping on a couch at Gearbox Software is the gigantic poster in the background which clearly shows the name of the next Borderlands 2 DLC, Tiny Tina's Assault on Dragon Keep.
The DLC was teased awhile back at PAX East when Gearbox did a presentation on the game in its current state and revealed some of their plans for the future of the series, which included raising the level cap in a standalone DLC which has since been released, and an upcoming player character based on the Psycho. The only thing they didn't fully reveal was the fourth and final campaign DLC, which was teased in the form of a Dungeons & Dragons game DM'd by Tiny Tina. Since then, Gearbox has remained quiet on the DLC.
However, the tweet by Borderlands 2 writer Anthony Burch, who goes by @reverandanthony on Twitter, has shed some light on the title of the next DLC and given us an idea of what it'll be about. The video teasing the DLC, it seems, wasn't very far off the mark from the actual content that they plan to release.
It's difficult to say whether the leak was genuine, as it was deleted just moments after it was posted, but we don't really care. It cannot be unseen. You can take a look at the screencap that Stealthybox managed to take before it was taken down.
It's also interesting to note that the game was updated late last month with support for additional DLC, so the new expansion shouldn't be too far behind.