Season 10, Episode 15 – The Locomotion Reverberation
With Sheldon hindering progress on the guidance-system project, Leonard and Stuart figure the only way they can get back on track is to engineer a distraction by getting him tickets to a historic railroad. Meanwhile, Penny and Amy spirit away new-mommy Bernadette for a girls’ night out, leaving baby Halley in the hands of Raj and Stuart.
What happens when hyperintelligent roommates Sheldon and Leonard meet Penny, a free-spirited beauty moving in next door, and realize they know next to nothing about life outside of the lab. Rounding out the crew are the smarmy Wolowitz, who thinks he’s as sexy as he is brainy, and Koothrappali, who suffers from an inability to speak in the presence of a woman.