[s12e15] The - Donation Oscillation

: Penny’s ex-boyfriend Zack and his wife Marissa ask Leonard to be their sperm donor because Zack is infertile.

: Although Penny initially said she was fine with it, she begins to have second thoughts. To prevent the donation—which requires Leonard to abstain from sex—she attempts to seduce him. [S12E15] The Donation Oscillation

: After Leonard declines, Sheldon expresses interest in donating his "superior" genetic material, but Amy immediately shuts him down. : Penny’s ex-boyfriend Zack and his wife Marissa

In the episode (Season 12, Episode 15), the story focuses on two main plotlines: Leonard’s potential sperm donation and a weightless "couple's trip" on a parabolic flight. The Donation Dilemma [S12E15] The Donation Oscillation