The Donation Oscillation

"The Donation Oscillation" is the fifteenth episode of the twelfth season of the sitcom The Big Bang Theory. The episode aired on Thursday, February 7, 2019.

Summary
Penny tries to an abstaining Leonard to ruin his "donation" for her ex-, Zack, and his, Marissa. Also, Wolowitz, Bernadette, Anu and Koothrappali turn Koothrappali's canceled into a couple’s trip aboard the "Vomit Comet."

Extended Plot
Zack and Marissa are visiting Leonard and Penny discussing Leonard’s pending ly donation. They are both grateful for Leonard’s help. Penny still thinks the subject is weird. The Johnson’s also think that it is weird that their kid will like Leonard. Zack adds that if it’s a, it’ll look like Penny. Typical Zack. Leonard needs to abstain from Penny to provide the most potent sample on Monday. They would like to have a, so Zack wants Leonard to keep thinking “Little boys. Little boys!” Sheldon wanders in on the pretext to borrow a and mentions how tall and  he is. Amy runs in and drags him home because Zack and Marissa want them to have Leonard’s and not his. As Sheldon leaves has also throws in his blue, no in his  and not being.

Raj is visiting Howard and is lamenting his that would have been that, though at least he is still with Anu. Howard adds the $3000 in to India that he can’t use. There is also the incredible that Howard had planned, through NASA he got four tickets on the “” allowing them to feel. Raj is excited and suggests a guy’s weekend just like in the good old. Howard adds that they were sad, and totally alone then

At the cafeteria Howard announces that they can all go on the "Vomit Comet" together. Sheldon is not interested in, while Penny’s father Wyatt is visiting over the weekend. Raj suggests then making it a and they could bring Bernadette and Anu. Howard plans to ask Stuart or Bert since he doesn’t think that Bernie would like to do that.

Penny comes into the and finds Leonard taking some  to help his. When Wyatt knocks on the door Penny asks Leonard not to bring up the subject of their, Zack and Marisa’s project or the. Wyatt comes in calling Penny “” and complimenting Leonard on his strong Leonard has been taking vitamins. Penny offers her dad a. He replies that he’ll one if she is since he knows that she’s not. Penny then blurts out about the Leonard-Zack project to take the subject off of their non-existent kids.

Howard enters the kitchen and asks if Bernie minds if he goes away that with Raj. The two were taking Anu and Stuart which bothers Bernadette that she wasn’t asked. Howard insists that she wouldn’t want to around weightless since she got  while in line to the  at Disneyland. First Howard says that he doesn’t want her to make everyone else miserable, but realizing what he said he invites her to go with them.

Back at the Hofstadters’ place, Leonard thanks Penny for throwing him under the. Wyatt wants to know why Leonard is okay with not wanting a with Penny, but wanting to have one for Penny’s dumb ex-. Penny supports Leonard, but is still okay with her dad making a scene about it. Wyatt then mentions about hiring out his prize for  purposes. Penny retorts that their situation is not like that though Leonard is fine being compared with a prize stud.

Leonard comes to bed talking about how much Wyatt likes him since Penny used to idiots. Penny does admit that she did a stud. Penny wants to make it up to him after throwing him to the earlier. She forgot that Leonard still had three days of ahead. Penny then comes to wearing a  outfit, snuggles up to Leonard and starts to read her comic book. “Bam! Pow! Take that Batman!”

The two couples are driving in the and Anu is so glad that Bernadette could come especially since Howard claimed that it wasn’t her thing. Bernadette snaps saying that Howard doesn’t know everything. Anu claims to be an junkie doing things like  and. Bernadette counters that she once jumped on the back of her and rolled through the  section. Howard added that just being married to her is a.

In Apartment 4A Sheldon comes out into the, fixes his and finds Leonard on their. Sheldon calls to Amy who comes in and is also surprised to find Leonard. He used his to come in and get away from Penny who wanted to have sex. Sheldon comments that he has been there and done that. Amy suggests that Penny still doesn’t want him to succeed. If Penny is objecting, Leonard wants her to tell him. He still wants to leave a little of himself behind in the. Amy adds that even if that is true, he would not be the kid’s father.

In the waiting room, the couples are being briefed for their  which will be the experience of their life. Bernie tells him that at 90, she gets weightless if she is holding onto three. While signing the injury and Bernadette has second thoughts about both of them doing it since they have kids. She was just trying to prove to Howard that he doesn’t know her as well as he thinks he does. And if she does it, she can prove him wrong. Anu thinks that she should just be honest. Bernadette agrees and tells Anu that she owes her $3000 for airline tickets.

Penny returns to her and her her dad after a long run interrupted by stopping at a  and a  chair. Her dad comments that she is not really mad at him and Leonard, but at herself. He says that she regrets her “no baby” plan. Penny agrees that she feels that she is letting everyone down. Wyatt tells her that she could never disappoint him, though her years were rough on him. She once stole a while drunk. He tells his that whatever she decides he is on her side. Leonard comes marching in and tells Wyatt to back off since it is his and Penny. Wyatt has already discussed it with Penny, but compliments Leonard on being forceful. Leonard then tells Penny that he has changed his mind and he’d be if there was a kid out there that he couldn’t be the father of. Penny agrees with him and then he asks if her to do that thing from last night; however, Wyatt is still within range.

Back in the airport waiting room, everyone is in though Bernadette declines to go. They have kids and she doesn’t think that they should both put themselves in danger. Howard cracks that he didn’t see that coming. Howard suggests that she go so she can prove herself right as the plane flies repeatedly up and down and up and down.

Now floating weightlessly Bernadette is yelling that she hates it so much. Anu says that she is proving her husband wrong. Now she LOVES doing it.

Leonard calls up Zack and Marissa declining to be their donor, but he does suggest that someone else is interested. While on the Amy is yelling at Sheldon that he is not going to do that. Sheldon says on the phone that apparently he is not allowed.

Credits

 * Guest starring:
 * Keith Carradine as Wyatt
 * Brian Thomas Smith as Zack
 * Rati Gupta as Anu
 * Lindsey Kraft as Marissa
 * Eric Nenniger as Neil
 * Teleplay: Steve Holland, Dave Goetsch & Maria Ferrari
 * Story: Bill Prady, Jeremy Howe & Adam Faberman

Critics

 * To be entered.
 * IMDb user review

Trivia

 * Penny's father Wyatt reappeared in this episode, marking his fifth appearance in the series.
 * Zack and his new wife Marissa also reappeared.
 * First episode of the last ten episodes.
 * Leonard thought about donating for Zack, but changed his mind. Not because of Penny, for himself. Penny would have respect his  whether she likes it or not.
 * Zack would have gone to Sheldon since the latter was willing to donate his sperm, Amy told Sheldon no.
 * Raj, Howard, Anu and Bernadette were going to . Bernadette was reluctant to go, but she changed her mind and go to prove Howard wrong.
 * Penny reveals that her 's name is Lisa.
 * Bernadette weighs pounds.
 * Penny stole a while drunk during her  years.
 * Sheldon and Amy have not had for three weeks.
 * Raj reveals that his parents had even had a bad when he was little.

Quotes
To be entered.