![](https://assets.tv24.co/channels/e4-l.webp)
Aired Sunday December 10,
5:35pm - 6:00pmon E4
The Big Bang Theory
Series 12 Episode 12: The Propagation PropositionPenny's ex-boyfriend Zack learns that he is infertile, so he asks Leonard for help. Then, Koothrappali attempts to mend things with his ex-fiancee Anu.
- Category
- Sitcom
- Original air date
- 2019-01-10
Cast and crew