The Big Bang Theory (2007–2019)
6 user 3 critic

The Propagation Proposition 

Penny's ex-boyfriend Zack learns that he is infertile, so he asks Leonard for help; Koothrappali attempts to mend things with his ex-fiancee Anu.


Mark Cendrowski


Chuck Lorre (created by), Bill Prady (created by) | 7 more credits »




Episode complete credited cast:
Johnny Galecki ... Leonard Hofstadter
Jim Parsons ... Sheldon Cooper
Kaley Cuoco ... Penny Hofstadter
Simon Helberg ... Howard Wolowitz
Kunal Nayyar ... Raj Koothrappali
Mayim Bialik ... Amy Farrah Fowler
Melissa Rauch ... Bernadette Rostenkowski
Brian George ... Dr. V.M. Koothrappali
Brian Thomas Smith ... Zack Johnson
Rati Gupta ... Anu
Lindsey Kraft ... Marissa Johnson
Shay Ali ... Greg


In Penny, Amy and Bernadette's girls' night out, they run into Penny's old boyfriend, Zack, who tells them that he has sold his company and retired a wealthy man, but perhaps most importantly that he has gotten married. He invites Penny and Leonard to a get together with him and his wife, Marissa, on their boat. Leonard feels uncomfortable enough as he has always been a bit jealous of Zack if only because he used to date Penny, but even more so now considering Zack's seeming success and financial security. But when Penny and Leonard do get together with Zack and Marissa, Penny may be the uncomfortable one when their hosts tell them the ulterior motive they had in inviting them. Their request may bring Leonard and Penny's relationship under greater scrutiny. And in what was the boys' games night in, the issue of Raj and the seeming end of his relationship with Anu keeps coming up. In thinking about it, Raj wants to get back together with her. In speaking to both Anu and his father, the... Written by Huggo

Plot Summary | Add Synopsis


Comedy | Romance


TV-PG | See all certifications »

Parents Guide:

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Did You Know?


First appearance of Lindsey Kraft as Zacks Wife. See more »


Sheldon refers to HDFS as "HDFS file system". The "FS" in the abbreviation, actually means "file system", so it is redundant to say it again, especially for Sheldon. See more »


Spoofs Love Actually (2003) See more »


History of Everything
Written by Barenaked Ladies
Performed by Barenaked Ladies
[Series theme song played during the opening titles]
See more »

User Reviews

This was OK episode
12 January 2019 | by pkperaSee all my reviews

I did not plan to review this episode, but seeing 2 reviews here - well, I will say what bothered me with them: 1 can not stand Bernadette, other took all it as some anti-baby agenda ... In other words, they really are not reviews, just expressing how can not stand some detail.

I think that this episode was OK for season 12, better than average in this season. Probably weakest part was Raj's 'romance' - but I think that it was bad from very start. Somehow it leads nowhere, and no way that someone is so stupid. But who knows what are plans for serial finale ? :-)

Pulling out Zack again was good idea, and that story can be developed over some episodes. And if I'm correct, we are at middle of season 12 - well, if it will be really 24 episodes.

5 of 7 people found this review helpful.  Was this review helpful to you? | Report this
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Release Date:

10 January 2019 (USA) See more »

Also Known As:

The Propagation Proposition See more »

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Technical Specs


Sound Mix:




Aspect Ratio:

16:9 HD
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