Season 2, Episode 22 - The Classified Materials Turbulence
Aired May 4, 2009
After Howard designs a special toilet for the International Space Station, the guys rush to develop a fix to stop the toilet malfunctioning in space. Meanwhile, Penny goes out on a second date with Stuart from the comic book store. When Leonard gets the impression things went awry on Penny and Stuart's date, he is thrilled to learn the reason why.