From Twitpocalypse:

“The Twitpocalypse is similar to the Y2K bug. Very soon the unique identifier associated to each tweet will exceed 2,147,483,6471

For some of your favorite third-party Twitter services not designed to handle such a case, the sequence will suddenly turn into negative numbers. At this point, they are very likely to malfunction or crash.

When will this happen? Check here often, and we will tell you how close we are to the Twitpocalypse.”

Props out to ShortFormBlog for finding this one.