Big Bang Theory season 7 episode 18 is to pick up from where last week's episode left off, so show fans can expect to see more of Sheldon and Howard's Houston adventures after that quite shaky plane ride. However, it seems that it wasn't only the ride that was experiencing turbulence, the same thing actually goes for Sheldon's relationship with his mother. What could be the reason behind this? Find out by tuning in on CBS at 8/7c or by watching Big Bang Theory season 7 episode 18 stream using the free online steam link available at the bottom.

Note: The following paragraphs contain major spoilers on the upcoming episode. If you don't want to spoil the fun and excitement, simply scroll down to the bottom and look for the free link to viewing the episode online there.

Previously, Howard asked Sheldon to come with him to a tour of NASA in Houston, and after that very turbulent plane ride, the two are likely to land safely on Houston and Sheldon would right away plan to surprise his mother by visiting her unannounced. But, it's not going to be the mother who will be surprised tonight; it's going to be Sheldon, who - according to several spoilers - will get the surprise of his life when he finds a naked man with his mother. Sounds like a very compromising situation, eh? Good thing Howard will be there to give our mean geek some friendly advice on how to handle the situation. Don't miss the all-new episode. Watch Big Bang Theory season 7 episode 18 online using the free online stream link at the bottom if you can't watch it tonight on its primetime airing at 8/7c on CBS.

In the official promotional clip for the upcoming Big Bang Theory season 7 episode 18, we can see Sheldon having trouble digesting what he saw when he arrived at his mom's place. The sneak peek even implies that Sheldon and his mom will end up fighting in their first conversation. A friendly Howard could then be seen talking to his blue friend, enlightening the other on how painful it may have been for his mother after his father left them. In the end, Sheldon will have a heartfelt conversation with his mother... of so we think. Catch the all-new episode which airs tonight. Watch Big Bang Theory season 7 episode 18 stream through the free online stream link below.

Meanwhile, back in the geeky gang's apartment, we will find out that the gang will engage into Raj's Murder Mystery after-dinner party. Stuart will be there to play victim. However, things will take a different turn when they decide to talk about where they see themselves 20 years after. Raj claims that Amy will win a Nobel Prize and that she will eventually buy Stuart's comic store and sell it, since it's blocking Sheldon's focus to their relationship. Meanwhile, Penny will be staying in London as an actress, but Leonard will be in the U.S. working as a famous scientist. Raj then claims that the couple will not end up together while Stuart claims that it is not going to happen. Finally, Raj dishes that he will be married to Beyoncé by then, so he would be very busy by the time all of them would agree to have a reunion dinner. Watch Big Bang Theory season 7 episode 18 stream through the free online stream link at the end of this post.

The official synopsis for Big Bang Theory season 7 episode 18 reads: "When Sheldon visits his Mom in Houston, he is forced to confront a new reality. Meanwhile, Raj's 'Murder Mystery' party starts some fights within the gang."

"The Mommy Observation" is scheduled to air this Thursday, March 13, at 8/7c on CBS. Watch Big Bang Theory season 7 episode 18 using this free online stream link here.