Penny has second thoughts about Leonard being a sperm donor and tries to nix his plans. Meanwhile, Raj, Anu, Howard, and Bernadette turn Raj's cancelled bachelor party into a couples' trip.
- Noodle Incident: According to Wyatt, Penny stole a horse drunk while in high school. Why or how is never explained.
- Reality Ensues: Discussed. Sheldon and Amy point out that while Leonard will be the biological father to Zack and Marissa's child, he won't be the exact father. It's what convinces Leonard to call off the agreement.