[Spoiler alert! The following contains spoilers for an upcoming episode of "The Big Bang Theory"]

Amy (Mayim Bialik) and Sheldon (Jim Parsons) are doing it.

After five long years together and a breakup earlier this season, the former couple will at last have sex on "The Big Bang Theory." The milestone episode was filmed Tuesday night and will air on Thursday, Dec. 17.

"After over five years of dating, we felt the time was right for Sheldon and Amy to finally consummate their relationship, and we're so excited for the audience to see the journey over the next several episodes," executive producer Steve Molaro said in a statement.

It is unclear if Amy and Sheldon will officially reconcile, but at least now we know what Professor Proton (Bob Newhart) will likely be advising Sheldon on in the episode.

"The Big Bang Theory" airs Thursdays on CBS.

Four4Four: Why Charlie Sheen REALLY came forward