‘Big Bang Theory’
Amy (Mayim Bialik) and Sheldon (Jim Parsons) will come clean to Mary (Laurie Metcalf) about their new living arrangements in "Big Bang Theory" Season 10, episode 12. CBS

CBS has just dropped the extended promo for “Big Bang Theory” Season 10, episode 12, titled “The Holiday Summation.”

The teaser opens with Sheldon (Jim Parsons) questioning Penny (Kaley Cuoco) and Leonard (Johnny Galecki) about the mistletoe that they placed in his old apartment. A pissed off Sheldon wonders if his friends don’t own a calendar because the holidays are almost over, but their decorations are incomplete. A second scene shows Sheldon apologizing to Bernadette (Melissa Rauch) and Amy (Mayim Bialik) for acting the way he did. He also confesses that he acted as such intentionally. A confused Bernadette wonders if Sheldon can really control his moods and outbursts.

Meanwhile, “The Holiday Summation” seems to be heavily centered on Sheldon. The character will get his ears pierced. Unfortunately, since he doesn’t have a high tolerance for pain, Sheldon will end up screaming and crying out in pain while doing so.

But these scenes are not the main highlight for episode 12. Sheldon and Amy will visit Mary Cooper (Laurie Metcalf) in Texas to tell her that they have moved in together. Mary won’t be able to hide the shock that she feels over the news. “Amy and I are living together in sin like a couple of New Yorkers,” he says.

Elsewhere, Bernadette and Howard (Simon Helberg) will have to go through sleepless nights as new parents with the arrival of their daughter, Hallie. The infant will be crying nonstop on Thursday night’s episode, and the new parents won’t know what to do to make her stop. Bernadette comes out of the room and rhetorically asks herself why she decided to have a baby at this point in her life.

“Big Bang Theory” Season 10, episode 12, titled “The Holiday Summation,” will air on Jan. 5 at 8 p.m. EST.