Episode Titles: Propagation
You are viewing a list of 1 The Big Bang Theory episode featuring "Propagation" in their title.
The Propagation Proposition
Season 12, Episode 12 - Aired January 10, 2019
Penny's ex-boyfriend, Zack (Brian Thomas Smith), and his wife want a baby, but when Zack is infertile, they ask Leonard for help. Also, Koothrappali attempts to mend things with his ex-fiancée, Anu.