"Mad Men" season 7 is the final season for the AMC series and John Slattery teases that the "Mad Men" season 7 finale might just leave your mouth hanging open at the end.

Speaking to the Huffington Post, John Slattery, who plays Roger Sterling on "Mad Men" season 7, gave some spoilers about the finale.

"The best part of the show is you think you know where it's going, but you don't know where it's going, and that's the best part about it. Your mouth is hanging open by the end of an episode or a season and you think, 'That's not what I expected,'" Slattery said, IB Times reports.

"That's why [creator] Matt [Weiner] is as good as he is. He knows because he knows what the audience wants -- you know, Joan and Roger -- that's not what he's necessarily interested in. That isn't to say that he's not going to give the audience what they want, but it's much more interesting to expect one thing and get another.

"And I don't think it's a waste of time if you don't get what you want," he added. "He's that good at setting up a story. I've stopped second-guessing. I think most of us on the show have stopped trying to figure out where it's going to go, because it never goes where you think it's going to go."

Christina Hendricks, who plays Joan Harris, also revealed some spoilers about the finale of "Mad Men" season 7.

"It's crazy, it's mad, it's just what you'd expect it to be. Every time a new script arrives we just fall on it and tear it apart looking for clues as to where our characters are going to wind up."

The seventh and final season of "Mad Men" will consist of 14 episodes that will be split into two 7-episode parts. "Mad Men" season 7 part one will wrap May 25, 2014 and the final episode will air May 2015. The first half is titled "The Beginning" while the second half is called "The End of an Era."