The Big Bang Theory season 10 returns with new episodes after its mid-season hiatus this Thursday (5 January) at 8pm EST on CBS Network. Episode 12 is titled, The Holiday Summation, where fans will finally find out what Sheldon's religious mother, Mary Cooper, thinks of her son living with his girlfriend, Amy Farrah Fowler.

The official synopsis for the episode reads as follows:

Sheldon and Amy visit Leonard and Penny for the first time since the holidays and share details about their terrible trip to Texas in The Big Bang Theory. Laurie Metcalf returns as Sheldon's mother, Mary.

Click here to watch the premiere episode via live stream online. You can also click here to watch it online (only in the US).

Sheldon and Amy will discuss their terrible trip to Texas with Leonard and Penny that involved the physicist getting his ears pierced and Mary finally getting to know about her son's living arrangements with Amy. Meanwhile, Howard and Bernadette, who welcomed daughter Halley in the mid-season finale, come to terms with what becoming parents entail.

A sneak-peek of the episode shows Sheldon and Amy returning home from their terrible Texas trip and complaining to Leonard and Penny about the Christmas decoration still not being taken down. Later, Penny gets a text from Bernadette telling the gang that they are running late because the baby threw up on Howard and then Howard threw up on himself.

According to a leaked report, Sheldon will tell his mother that he is living together with Amy, but much to his surprise, Mary is not offended at all by the revelation. His mother tells them a story about how three-year-old Sheldon named 1,000 different trains. Mary was convinced then that no girl would ever board any of them. Upon hearing this, Sheldon is offended that his mother thought that he would never be married and leaves.

Later, he returns and starts acting dumb, by wearing underwear on his head, thinking his mother wants him to be as dumb as his other siblings.