[s12e15] The Donation Oscillation -

: This episode marks the final appearances of Zack Johnson and Penny's father, Wyatt.

: After Leonard declines, Sheldon expresses interest in donating his "superior" genetic material, but Amy immediately shuts him down. [S12E15] The Donation Oscillation

: Determined to prove Howard wrong, Bernadette goes on the flight. She spends the experience screaming in terror but ultimately claims to love it just to spite him. Key Trivia : This episode marks the final appearances of

: Penny’s ex-boyfriend Zack and his wife Marissa ask Leonard to be their sperm donor because Zack is infertile. She spends the experience screaming in terror but

: During the episode, Wyatt reveals a "noodle incident" from Penny's past: she once drunkenly stole a horse in high school.

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

: Raj and Anu’s canceled bachelor party is repurposed into a group outing on a "Vomit Comet" (a weightless flight) for Raj, Anu, Howard, and Bernadette.