CBS

Season 6: Episode 24 - The Bon Voyage Reaction

The Bon Voyage Reaction: Leonard gets an opportunity to work on a Stephen Hawking project but is apprehensive because it will keep him away from Penny for three months. Penny gets some advice from Bernadette, since she was in a similar position while Wolowitz was in space, and she ultimately decides that she can handle it. Penny drops Leonard off at the airport, then goes to see Koothrappali, who just learned that Lucy broke up with him because she felt too uncomfortable. As Penny and Koothrappali talk, they get into some emotional issues and both wind up crying. Penny eventually realizes that Koothrappali has had nothing to drink, indicating that he has finally overcome his fear of talking to women.