When Leonard sees Penny kissing a man in front of her apartment door, he is devastated thinking she has "rejected" him. The guys convince him to ask someone out at work, so he asks out fellow scientist Leslie Winkle (Sara Gilbert), who preemptively turns him down. As Leonard slips deeper into his depression, which involves thinking about buying a cat, Sheldon points out that he was not actually rejected by Penny, as he had not asked her out. Leonard agrees and promptly asks Penny out to dinner, but she mistakes his invite as an invitation to hang with all the guys. Despite being aware of this, Leonard keeps the date and makes up excuses as to why the guys were absent.
On the date, Penny mentions the man Leonard saw was not her boyfriend, but that she has a habit of having weekend-long casual sex encounters to get over relationships. Excited, Leonard begins to become more confident but he accidentally hurts himself and Penny has to take him home. In the end, Leonard does not get the courage to reveal his true feelings to Penny, even though she suspected what he was up to.
Recurring character: Sara Gilbert as Leslie Winkle
Title reference: One of the names that Leonard was considering for his cat.